From 58ee50892a4b14a32b98385c083f1736b7f809fc Mon Sep 17 00:00:00 2001
From: GitHub Actions <actions@github.com>
Date: Tue, 5 Mar 2024 00:09:09 +0000
Subject: [PATCH] site deploy

Auto-generated via {sandpaper}
Source  : cf0c3f31a34e1d2fb9c248d45de37cf94b47bc40
Branch  : md-outputs
Author  : GitHub Actions <actions@github.com>
Time    : 2024-02-16 22:55:01 +0000
Message : markdown source builds

Auto-generated via {sandpaper}
Source  : fee164fe26b7ae86ef4164ae02f27e1a59b53236
Branch  : main
Author  : Allen Lee <alee@users.noreply.github.com>
Time    : 2024-02-16 22:53:50 +0000
Message : Merge pull request #671 from sborrego/patch-2

fix conditional logic ordering
---
 01-run-quit.html                     |   46 +-
 02-variables.html                    |   92 +-
 03-types-conversion.html             |  102 +-
 04-built-in.html                     |   93 +-
 05-coffee.html                       |    2 +-
 06-libraries.html                    |  117 +-
 07-reading-tabular.html              |   59 +-
 08-data-frames.html                  |  328 ++--
 09-plotting.html                     |  190 ++-
 10-lunch.html                        |    2 +-
 11-lists.html                        |  146 +-
 12-for-loops.html                    |  232 +--
 13-conditionals.html                 |  266 +--
 14-looping-data-sets.html            |   99 +-
 15-coffee.html                       |    2 +-
 16-writing-functions.html            |  351 ++--
 17-scope.html                        |   32 +-
 18-style.html                        |  181 +-
 19-wrap.html                         |    2 +-
 20-feedback.html                     |    2 +-
 404.html                             |    4 +-
 CODE_OF_CONDUCT.html                 |    2 +-
 LICENSE.html                         |    2 +-
 aio.html                             | 2288 ++++++++++++-------------
 design.html                          |    9 +-
 discuss.html                         |    2 +-
 exercises.html                       |    2 +-
 images.html                          |   11 +-
 index.html                           |    4 +-
 instructor-notes.html                |    4 +-
 instructor/01-run-quit.html          |   46 +-
 instructor/02-variables.html         |   92 +-
 instructor/03-types-conversion.html  |  102 +-
 instructor/04-built-in.html          |   93 +-
 instructor/05-coffee.html            |    2 +-
 instructor/06-libraries.html         |  117 +-
 instructor/07-reading-tabular.html   |   59 +-
 instructor/08-data-frames.html       |  330 ++--
 instructor/09-plotting.html          |  190 ++-
 instructor/10-lunch.html             |    2 +-
 instructor/11-lists.html             |  146 +-
 instructor/12-for-loops.html         |  232 +--
 instructor/13-conditionals.html      |  266 +--
 instructor/14-looping-data-sets.html |   99 +-
 instructor/15-coffee.html            |    2 +-
 instructor/16-writing-functions.html |  351 ++--
 instructor/17-scope.html             |   32 +-
 instructor/18-style.html             |  181 +-
 instructor/19-wrap.html              |    2 +-
 instructor/20-feedback.html          |    2 +-
 instructor/404.html                  |    4 +-
 instructor/CODE_OF_CONDUCT.html      |    2 +-
 instructor/LICENSE.html              |    2 +-
 instructor/aio.html                  | 2290 +++++++++++++-------------
 instructor/design.html               |    9 +-
 instructor/discuss.html              |    2 +-
 instructor/exercises.html            |    2 +-
 instructor/images.html               |   11 +-
 instructor/index.html                |    4 +-
 instructor/instructor-notes.html     |    4 +-
 instructor/key-points.html           |    4 +-
 instructor/profiles.html             |    4 +-
 instructor/reference.html            |   44 +-
 key-points.html                      |    4 +-
 pkgdown.yml                          |    4 +-
 profiles.html                        |    4 +-
 reference.html                       |   44 +-
 67 files changed, 4716 insertions(+), 4740 deletions(-)

diff --git a/01-run-quit.html b/01-run-quit.html
index d0035198a..62ef2fdc5 100644
--- a/01-run-quit.html
+++ b/01-run-quit.html
@@ -476,13 +476,12 @@ <h3 class="card-title">Objectives</h3>
 result</li>
 <li>Type code into the browser and see the results after your JupyterLab
 server has finished executing your code</li>
-</ul><div id="jupyterlab-what-about-jupyter-notebooks" class="callout callout">
+</ul><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="jupyterlab-what-about-jupyter-notebooks" class="callout-inner">
-<h3 class="callout-title">JupyterLab? What about Jupyter notebooks?<a class="anchor" aria-label="anchor" href="#jupyterlab-what-about-jupyter-notebooks"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="jupyterlab-what-about-jupyter-notebooks">JupyterLab? What about Jupyter notebooks?<a class="anchor" aria-label="anchor" href="#jupyterlab-what-about-jupyter-notebooks"></a></h3>
 <div class="callout-content">
 <p>JupyterLab is the <a href="https://jupyterlab.readthedocs.io/en/stable/getting_started/overview.html#overview" class="external-link">next
 stage in the evolution of the Jupyter Notebook</a>. If you have prior
@@ -516,7 +515,7 @@ <h3 id="macos---command-line">macOS - Command Line<a class="anchor" aria-label="
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">BASH<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
+<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
 </div>
 </div>
 <div class="section level3">
@@ -529,7 +528,7 @@ <h3 id="windows-users---command-line">Windows Users - Command Line<a class="anch
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">BASH<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
+<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
 </div>
 </div>
 <div class="section level3">
@@ -598,13 +597,12 @@ <h3 id="menu-bar">Menu Bar<a class="anchor" aria-label="anchor" href="#menu-bar"
 <li>
 <strong>Help:</strong> A list of JupyterLab and kernel help
 links.</li>
-</ul><div id="kernels" class="callout callout">
+</ul><div id="callout2" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="kernels" class="callout-inner">
-<h3 class="callout-title">Kernels<a class="anchor" aria-label="anchor" href="#kernels"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="kernels">Kernels<a class="anchor" aria-label="anchor" href="#kernels"></a></h3>
 <div class="callout-content">
 <p>The JupyterLab <a href="https://jupyterlab.readthedocs.io/en/stable/user/documents_kernels.html" class="external-link">docs</a>
 define kernels as “separate processes started by the server that runs
@@ -682,13 +680,12 @@ <h3 id="main-work-area">Main Work Area<a class="anchor" aria-label="anchor" href
 notebook documentation</a>.</p>
 <p align="center">
 <img alt="Example Jupyter Notebook" src="fig/0_jupyterlab_notebook_screenshot.png" width="750" class="figure"></p>
-<div id="how-its-stored" class="callout callout">
+<div id="callout3" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="how-its-stored" class="callout-inner">
-<h3 class="callout-title">How It’s Stored<a class="anchor" aria-label="anchor" href="#how-its-stored"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="how-its-stored">How It’s Stored<a class="anchor" aria-label="anchor" href="#how-its-stored"></a></h3>
 <div class="callout-content">
 <ul><li>The notebook file is stored in a format called JSON.</li>
 <li>Just like a webpage, what’s saved looks different from what you see
@@ -735,13 +732,12 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </div>
 </div>
 </div>
-<div id="code-vs.-text" class="callout callout">
+<div id="callout4" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="code-vs.-text" class="callout-inner">
-<h3 class="callout-title">Code vs. Text<a class="anchor" aria-label="anchor" href="#code-vs.-text"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="code-vs--text">Code vs. Text<a class="anchor" aria-label="anchor" href="#code-vs--text"></a></h3>
 <div class="callout-content">
 <p>Jupyter mixes code and text in different types of blocks, called
 cells. We often use the term “code” to mean “the source code of software
@@ -982,8 +978,8 @@ <h3 class="callout-title">More Math<a class="anchor" aria-label="anchor" href="#
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="dv">7</span> <span class="op">*</span> <span class="dv">3</span></span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="dv">2</span> <span class="op">+</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="dv">7</span> <span class="op">*</span> <span class="dv">3</span></span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="dv">2</span> <span class="op">+</span> <span class="dv">1</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -999,7 +995,7 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="dv">3</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="dv">3</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -1020,8 +1016,8 @@ <h3 class="callout-title">Change an Existing Cell from Code to
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span></span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(x)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span></span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a><span class="bu">print</span>(x)</span></code></pre>
 </div>
 <p>And then run it with <kbd>Shift</kbd>+<kbd>Return</kbd> to be sure
 that it works as a code cell. Now go back to the cell and use
@@ -1045,7 +1041,7 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span> <span class="bu">print</span>(x)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span> <span class="bu">print</span>(x)</span></code></pre>
 </div>
 </div>
 </div>
@@ -1190,7 +1186,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/01-run-quit.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-06-07",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/02-variables.html b/02-variables.html
index a15a6eda3..51cd3b212 100644
--- a/02-variables.html
+++ b/02-variables.html
@@ -456,8 +456,8 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">42</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>first_name <span class="op">=</span> <span class="st">'Ahmed'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">42</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>first_name <span class="op">=</span> <span class="st">'Ahmed'</span></span></code></pre>
 </div>
 </li>
 </ul></section><section id="use-print-to-display-values."><h2 class="section-heading">Use <code>print</code> to display values.<a class="anchor" aria-label="anchor" href="#use-print-to-display-values."></a>
@@ -476,7 +476,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(first_name, <span class="st">'is'</span>, age, <span class="st">'years old'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(first_name, <span class="st">'is'</span>, age, <span class="st">'years old'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -495,7 +495,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(last_name)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="bu">print</span>(last_name)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -510,13 +510,12 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <ul><li>The last line of an error message is usually the most
 informative.</li>
 <li>We will look at error messages in detail <a href="17-scope.html#reading-error-messages">later</a>.</li>
-</ul><div id="variables-persist-between-cells" class="callout callout">
+</ul><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="variables-persist-between-cells" class="callout-inner">
-<h3 class="callout-title">Variables Persist Between Cells<a class="anchor" aria-label="anchor" href="#variables-persist-between-cells"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="variables-persist-between-cells">Variables Persist Between Cells<a class="anchor" aria-label="anchor" href="#variables-persist-between-cells"></a></h3>
 <div class="callout-content">
 <p>Be aware that it is the <em>order</em> of execution of cells that is
 important in a Jupyter notebook, not the order in which they appear.
@@ -529,12 +528,12 @@ <h3 class="callout-title">Variables Persist Between Cells<a class="anchor" aria-
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(myval)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a><span class="bu">print</span>(myval)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>myval <span class="op">=</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>myval <span class="op">=</span> <span class="dv">1</span></span></code></pre>
 </div>
 <p>If you execute this in order, the first cell will give an error.
 However, if you run the first cell <em>after</em> the second cell it
@@ -554,8 +553,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> age <span class="op">+</span> <span class="dv">3</span></span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Age in three years:'</span>, age)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a>age <span class="op">=</span> age <span class="op">+</span> <span class="dv">3</span></span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Age in three years:'</span>, age)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -574,13 +573,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <li>Indices are numbered from 0.</li>
 <li>Use the position’s index in square brackets to get the character at
 that position.</li>
-</ul><figure><img src="fig/2_indexing.svg" alt="" class="figure mx-auto d-block"><figcaption>A line of Python code, print(atom_name[0]),
+</ul><figure><img src="fig/2_indexing.svg" alt="A line of Python code, print(atom_name[0]), demonstrates that using the zero index will output just the initial letter, in this case ‘h’ for helium." class="figure mx-auto d-block"><div class="figcaption">A line of Python code, print(atom_name[0]),
 demonstrates that using the zero index will output just the initial
-letter, in this case ‘h’ for helium.</figcaption></figure><div class="codewrapper sourceCode" id="cb10">
+letter, in this case ‘h’ for helium.</div>
+</figure><div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'helium'</span></span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'helium'</span></span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -608,8 +608,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'sodium'</span></span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>:<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'sodium'</span></span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>:<span class="dv">3</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -622,7 +622,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="st">'helium'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="st">'helium'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -644,9 +644,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>flabadab <span class="op">=</span> <span class="dv">42</span></span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a>ewr_422_yY <span class="op">=</span> <span class="st">'Ahmed'</span></span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(ewr_422_yY, <span class="st">'is'</span>, flabadab, <span class="st">'years old'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>flabadab <span class="op">=</span> <span class="dv">42</span></span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a>ewr_422_yY <span class="op">=</span> <span class="st">'Ahmed'</span></span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a><span class="bu">print</span>(ewr_422_yY, <span class="st">'is'</span>, flabadab, <span class="st">'years old'</span>)</span></code></pre>
 </div>
 <ul><li>Use meaningful variable names to help other people understand what
 the program does.</li>
@@ -664,12 +664,12 @@ <h3 class="callout-title">Swapping Values<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Command  # Value of x   # Value of y   # Value of swap #</span></span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> <span class="fl">1.0</span>    <span class="co">#              #              #               #</span></span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a>y <span class="op">=</span> <span class="fl">3.0</span>    <span class="co">#              #              #               #</span></span>
-<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a>swap <span class="op">=</span> x   <span class="co">#              #              #               #</span></span>
-<span id="cb17-5"><a href="#cb17-5" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> y      <span class="co">#              #              #               #</span></span>
-<span id="cb17-6"><a href="#cb17-6" aria-hidden="true" tabindex="-1"></a>y <span class="op">=</span> swap   <span class="co">#              #              #               #</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="co"># Command  # Value of x   # Value of y   # Value of swap #</span></span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>x <span class="op">=</span> <span class="fl">1.0</span>    <span class="co">#              #              #               #</span></span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a>y <span class="op">=</span> <span class="fl">3.0</span>    <span class="co">#              #              #               #</span></span>
+<span id="cb17-4"><a href="#cb17-4" tabindex="-1"></a>swap <span class="op">=</span> x   <span class="co">#              #              #               #</span></span>
+<span id="cb17-5"><a href="#cb17-5" tabindex="-1"></a>x <span class="op">=</span> y      <span class="co">#              #              #               #</span></span>
+<span id="cb17-6"><a href="#cb17-6" tabindex="-1"></a>y <span class="op">=</span> swap   <span class="co">#              #              #               #</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -679,7 +679,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -712,9 +712,9 @@ <h3 class="callout-title">Predicting Values<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'left'</span></span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>position <span class="op">=</span> initial</span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'right'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'left'</span></span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>position <span class="op">=</span> initial</span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'right'</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -724,12 +724,12 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(position)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a><span class="bu">print</span>(position)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -764,7 +764,7 @@ <h3 class="callout-title">Challenge<a class="anchor" aria-label="anchor" href="#
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Numbers are not strings or sequences and Python will raise an error
 if you try to perform an index operation on a number. In the <a href="03-types-conversion.html">next lesson on types and type
@@ -775,8 +775,8 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">=</span> <span class="dv">123</span></span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>a <span class="op">=</span> <span class="dv">123</span></span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -786,8 +786,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">=</span> <span class="bu">str</span>(<span class="dv">123</span>)</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a>a <span class="op">=</span> <span class="bu">str</span>(<span class="dv">123</span>)</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -820,7 +820,7 @@ <h3 class="callout-title">Choosing a Name<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p><code>minutes</code> is better because <code>min</code> might mean
 something like “minimum” (and actually is an existing built-in function
@@ -841,8 +841,8 @@ <h3 class="callout-title">Slicing practice<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'carbon'</span></span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'atom_name[1:3] is:'</span>, atom_name[<span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'carbon'</span></span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'atom_name[1:3] is:'</span>, atom_name[<span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -852,7 +852,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -875,7 +875,7 @@ <h3 class="callout-title">Slicing concepts<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>species_name <span class="op">=</span> <span class="st">"Acacia buxifolia"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>species_name <span class="op">=</span> <span class="st">"Acacia buxifolia"</span></span></code></pre>
 </div>
 <p>What would these expressions return?</p>
 <ol style="list-style-type: decimal"><li><code>species_name[2:8]</code></li>
@@ -900,7 +900,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solutions</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <ol style="list-style-type: decimal"><li>
 <code>species_name[2:8]</code> returns the substring
@@ -1014,7 +1014,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/02-variables.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/03-types-conversion.html b/03-types-conversion.html
index 0b2ea0010..c1e494270 100644
--- a/03-types-conversion.html
+++ b/03-types-conversion.html
@@ -457,7 +457,7 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="dv">52</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="dv">52</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -467,8 +467,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>fitness <span class="op">=</span> <span class="st">'average'</span></span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(fitness))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a>fitness <span class="op">=</span> <span class="st">'average'</span></span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(fitness))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -482,7 +482,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span> <span class="op">-</span> <span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span> <span class="op">-</span> <span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -492,7 +492,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'hello'</span> <span class="op">-</span> <span class="st">'h'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'hello'</span> <span class="op">-</span> <span class="st">'h'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -510,8 +510,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>full_name <span class="op">=</span> <span class="st">'Ahmed'</span> <span class="op">+</span> <span class="st">' '</span> <span class="op">+</span> <span class="st">'Walsh'</span></span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(full_name)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>full_name <span class="op">=</span> <span class="st">'Ahmed'</span> <span class="op">+</span> <span class="st">' '</span> <span class="op">+</span> <span class="st">'Walsh'</span></span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="bu">print</span>(full_name)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -526,8 +526,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>separator <span class="op">=</span> <span class="st">'='</span> <span class="op">*</span> <span class="dv">10</span></span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(separator)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>separator <span class="op">=</span> <span class="st">'='</span> <span class="op">*</span> <span class="dv">10</span></span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="bu">print</span>(separator)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -541,7 +541,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(full_name))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(full_name))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -552,7 +552,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="dv">52</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="dv">52</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -571,7 +571,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -590,8 +590,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="bu">int</span>(<span class="st">'2'</span>))</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">str</span>(<span class="dv">1</span>) <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="bu">int</span>(<span class="st">'2'</span>))</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">str</span>(<span class="dv">1</span>) <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -607,8 +607,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'half is'</span>, <span class="dv">1</span> <span class="op">/</span> <span class="fl">2.0</span>)</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'three squared is'</span>, <span class="fl">3.0</span> <span class="op">**</span> <span class="dv">2</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'half is'</span>, <span class="dv">1</span> <span class="op">/</span> <span class="fl">2.0</span>)</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'three squared is'</span>, <span class="fl">3.0</span> <span class="op">**</span> <span class="dv">2</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -624,10 +624,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">1</span></span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a>variable_two <span class="op">=</span> <span class="dv">5</span> <span class="op">*</span> variable_one</span>
-<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">2</span></span>
-<span id="cb23-4"><a href="#cb23-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first is'</span>, variable_one, <span class="st">'and second is'</span>, variable_two)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">1</span></span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a>variable_two <span class="op">=</span> <span class="dv">5</span> <span class="op">*</span> variable_one</span>
+<span id="cb23-3"><a href="#cb23-3" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">2</span></span>
+<span id="cb23-4"><a href="#cb23-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first is'</span>, variable_one, <span class="st">'and second is'</span>, variable_two)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -658,7 +658,7 @@ <h3 class="callout-title">Fractions<a class="anchor" aria-label="anchor" href="#
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>It is a floating-point number (often abbreviated “float”). It is
 possible to find out by using the built-in function
@@ -666,7 +666,7 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="fl">3.4</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="fl">3.4</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -694,15 +694,15 @@ <h3 class="callout-title">Automatic Type Conversion<a class="anchor" aria-label=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>It is a float: integers are automatically converted to floats as
 necessary.</p>
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="fl">3.25</span> <span class="op">+</span> <span class="dv">4</span></span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result, <span class="st">'is'</span>, <span class="bu">type</span>(result))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>result <span class="op">=</span> <span class="fl">3.25</span> <span class="op">+</span> <span class="dv">4</span></span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a><span class="bu">print</span>(result, <span class="st">'is'</span>, <span class="bu">type</span>(result))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -740,7 +740,7 @@ <h3 class="callout-title">Choose a Type<a class="anchor" aria-label="anchor" hre
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>The answers to the questions are:</p>
 <ol style="list-style-type: decimal"><li>Integer, since the number of days would lie between 1 and 365.</li>
@@ -773,9 +773,9 @@ <h3 class="callout-title">Division Types<a class="anchor" aria-label="anchor" hr
 <div class="codewrapper sourceCode" id="cb29">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 // 3:'</span>, <span class="dv">5</span> <span class="op">//</span> <span class="dv">3</span>)</span>
-<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 / 3:'</span>, <span class="dv">5</span> <span class="op">/</span> <span class="dv">3</span>)</span>
-<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 % 3:'</span>, <span class="dv">5</span> <span class="op">%</span> <span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 // 3:'</span>, <span class="dv">5</span> <span class="op">//</span> <span class="dv">3</span>)</span>
+<span id="cb29-2"><a href="#cb29-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 / 3:'</span>, <span class="dv">5</span> <span class="op">/</span> <span class="dv">3</span>)</span>
+<span id="cb29-3"><a href="#cb29-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 % 3:'</span>, <span class="dv">5</span> <span class="op">%</span> <span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -796,7 +796,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>We want the minimum number of surveys that reaches everyone once,
 which is the rounded up value of
@@ -808,11 +808,11 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>num_subjects <span class="op">=</span> <span class="dv">600</span></span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a>num_per_survey <span class="op">=</span> <span class="dv">42</span></span>
-<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a>num_surveys <span class="op">=</span> (num_subjects <span class="op">-</span> <span class="dv">1</span>) <span class="op">//</span> num_per_survey <span class="op">+</span> <span class="dv">1</span></span>
-<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb31-5"><a href="#cb31-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(num_subjects, <span class="st">'subjects,'</span>, num_per_survey, <span class="st">'per survey:'</span>, num_surveys)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>num_subjects <span class="op">=</span> <span class="dv">600</span></span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a>num_per_survey <span class="op">=</span> <span class="dv">42</span></span>
+<span id="cb31-3"><a href="#cb31-3" tabindex="-1"></a>num_surveys <span class="op">=</span> (num_subjects <span class="op">-</span> <span class="dv">1</span>) <span class="op">//</span> num_per_survey <span class="op">+</span> <span class="dv">1</span></span>
+<span id="cb31-4"><a href="#cb31-4" tabindex="-1"></a></span>
+<span id="cb31-5"><a href="#cb31-5" tabindex="-1"></a><span class="bu">print</span>(num_subjects, <span class="st">'subjects,'</span>, num_per_survey, <span class="st">'per survey:'</span>, num_surveys)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -837,8 +837,8 @@ <h3 class="callout-title">Strings to Numbers<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb33">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"3.4"</span>))</span>
-<span id="cb33-2"><a href="#cb33-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"float to int:"</span>, <span class="bu">int</span>(<span class="fl">3.4</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"3.4"</span>))</span>
+<span id="cb33-2"><a href="#cb33-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"float to int:"</span>, <span class="bu">int</span>(<span class="fl">3.4</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -851,7 +851,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"Hello world!"</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"Hello world!"</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -870,7 +870,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"fractional string to int:"</span>, <span class="bu">int</span>(<span class="st">"3.4"</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"fractional string to int:"</span>, <span class="bu">int</span>(<span class="st">"3.4"</span>))</span></code></pre>
 </div>
 </div>
 </div>
@@ -880,7 +880,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>What do you expect this program to do? It would not be so
 unreasonable to expect the Python 3 <code>int</code> command to convert
@@ -890,7 +890,7 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb38">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a><span class="bu">int</span>(<span class="st">"3.4"</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" tabindex="-1"></a><span class="bu">int</span>(<span class="st">"3.4"</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -907,7 +907,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb40">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a><span class="bu">int</span>(<span class="bu">float</span>(<span class="st">"3.4"</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" tabindex="-1"></a><span class="bu">int</span>(<span class="bu">float</span>(<span class="st">"3.4"</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -931,9 +931,9 @@ <h3 class="callout-title">Arithmetic with Different Types<a class="anchor" aria-
 <div class="codewrapper sourceCode" id="cb42">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" aria-hidden="true" tabindex="-1"></a>first <span class="op">=</span> <span class="fl">1.0</span></span>
-<span id="cb42-2"><a href="#cb42-2" aria-hidden="true" tabindex="-1"></a>second <span class="op">=</span> <span class="st">"1"</span></span>
-<span id="cb42-3"><a href="#cb42-3" aria-hidden="true" tabindex="-1"></a>third <span class="op">=</span> <span class="st">"1.1"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" tabindex="-1"></a>first <span class="op">=</span> <span class="fl">1.0</span></span>
+<span id="cb42-2"><a href="#cb42-2" tabindex="-1"></a>second <span class="op">=</span> <span class="st">"1"</span></span>
+<span id="cb42-3"><a href="#cb42-3" tabindex="-1"></a>third <span class="op">=</span> <span class="st">"1.1"</span></span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li><code>first + float(second)</code></li>
 <li><code>float(second) + float(third)</code></li>
@@ -949,7 +949,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Show me the solution</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <p>Answer: 1 and 4</p>
 </div>
@@ -971,9 +971,9 @@ <h3 class="callout-title">Complex Numbers<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb43">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a>a_complex_number <span class="op">=</span> <span class="dv">6</span> <span class="op">+</span> <span class="ot">2j</span></span>
-<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.real)</span>
-<span id="cb43-3"><a href="#cb43-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.imag)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" tabindex="-1"></a>a_complex_number <span class="op">=</span> <span class="dv">6</span> <span class="op">+</span> <span class="ot">2j</span></span>
+<span id="cb43-2"><a href="#cb43-2" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.real)</span>
+<span id="cb43-3"><a href="#cb43-3" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.imag)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -994,7 +994,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
 <div class="accordion-body">
 <ol style="list-style-type: decimal"><li>Standard mathematics treatments typically use <code>i</code> to
 denote an imaginary number. However, from media reports it was an early
@@ -1092,7 +1092,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/03-types-conversion.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/04-built-in.html b/04-built-in.html
index b478bc88b..d5d9e7ce6 100644
--- a/04-built-in.html
+++ b/04-built-in.html
@@ -445,8 +445,8 @@ <h3 class="card-title">Objectives</h3>
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="co"># This sentence isn't executed by Python.</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>adjustment <span class="op">=</span> <span class="fl">0.5</span>   <span class="co"># Neither is this - anything after '#' is ignored.</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="co"># This sentence isn't executed by Python.</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>adjustment <span class="op">=</span> <span class="fl">0.5</span>   <span class="co"># Neither is this - anything after '#' is ignored.</span></span></code></pre>
 </div>
 </section><section id="a-function-may-take-zero-or-more-arguments."><h2 class="section-heading">A function may take zero or more arguments.<a class="anchor" aria-label="anchor" href="#a-function-may-take-zero-or-more-arguments."></a>
 </h2>
@@ -468,9 +468,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'before'</span>)</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>()</span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'after'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'before'</span>)</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a><span class="bu">print</span>()</span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'after'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -488,8 +488,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">print</span>(<span class="st">'example'</span>)</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of print is'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">print</span>(<span class="st">'example'</span>)</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of print is'</span>, result)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -509,8 +509,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>))</span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">min</span>(<span class="st">'a'</span>, <span class="st">'A'</span>, <span class="st">'0'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>))</span>
+<span id="cb6-2"><a href="#cb6-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">min</span>(<span class="st">'a'</span>, <span class="st">'A'</span>, <span class="st">'0'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -531,7 +531,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="st">'a'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="st">'a'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -550,7 +550,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -561,7 +561,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>, <span class="dv">1</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>, <span class="dv">1</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -579,13 +579,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>  <span class="co"># creation of a string object </span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(my_string))       <span class="co"># the len function takes a string as an argument and returns the length of the string</span></span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.swapcase()) <span class="co"># calling the swapcase method on the my_string object</span></span>
-<span id="cb14-6"><a href="#cb14-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb14-7"><a href="#cb14-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.<span class="fu">__len__</span>())  <span class="co"># calling the internal __len__ method on the my_string object, used by len(my_string)</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>  <span class="co"># creation of a string object </span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a></span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(my_string))       <span class="co"># the len function takes a string as an argument and returns the length of the string</span></span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a></span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a><span class="bu">print</span>(my_string.swapcase()) <span class="co"># calling the swapcase method on the my_string object</span></span>
+<span id="cb14-6"><a href="#cb14-6" tabindex="-1"></a></span>
+<span id="cb14-7"><a href="#cb14-7" tabindex="-1"></a><span class="bu">print</span>(my_string.<span class="fu">__len__</span>())  <span class="co"># calling the internal __len__ method on the my_string object, used by len(my_string)</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -599,10 +599,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.isupper())          <span class="co"># Not all the letters are uppercase</span></span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.upper())            <span class="co"># This capitalizes all the letters</span></span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.upper().isupper())  <span class="co"># Now all the letters are uppercase</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a><span class="bu">print</span>(my_string.isupper())          <span class="co"># Not all the letters are uppercase</span></span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a><span class="bu">print</span>(my_string.upper())            <span class="co"># This capitalizes all the letters</span></span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a></span>
+<span id="cb16-4"><a href="#cb16-4" tabindex="-1"></a><span class="bu">print</span>(my_string.upper().isupper())  <span class="co"># Now all the letters are uppercase</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -618,7 +618,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(<span class="bu">round</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a><span class="bu">help</span>(<span class="bu">round</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -647,8 +647,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Forgot to close the quote marks around the string.</span></span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>name <span class="op">=</span> <span class="st">'Feng</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a><span class="co"># Forgot to close the quote marks around the string.</span></span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>name <span class="op">=</span> <span class="st">'Feng</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -661,8 +661,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a><span class="co"># An extra '=' in the assignment.</span></span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> <span class="op">=</span> <span class="dv">52</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a><span class="co"># An extra '=' in the assignment.</span></span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>age <span class="op">=</span> <span class="op">=</span> <span class="dv">52</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -676,7 +676,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"hello world"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"hello world"</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -702,8 +702,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">53</span></span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a>remaining <span class="op">=</span> <span class="dv">100</span> <span class="op">-</span> aege <span class="co"># mis-spelled 'age'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">53</span></span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a>remaining <span class="op">=</span> <span class="dv">100</span> <span class="op">-</span> aege <span class="co"># mis-spelled 'age'</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -732,8 +732,8 @@ <h3 class="callout-title">What Happens When<a class="anchor" aria-label="anchor"
 </ol><div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>radiance <span class="op">=</span> <span class="fl">1.0</span></span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a>radiance <span class="op">=</span> <span class="bu">max</span>(<span class="fl">2.1</span>, <span class="fl">2.0</span> <span class="op">+</span> <span class="bu">min</span>(radiance, <span class="fl">1.1</span> <span class="op">*</span> radiance <span class="op">-</span> <span class="fl">0.5</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>radiance <span class="op">=</span> <span class="fl">1.0</span></span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a>radiance <span class="op">=</span> <span class="bu">max</span>(<span class="fl">2.1</span>, <span class="fl">2.0</span> <span class="op">+</span> <span class="bu">min</span>(radiance, <span class="fl">1.1</span> <span class="op">*</span> radiance <span class="op">-</span> <span class="fl">0.5</span>))</span></code></pre>
 </div>
 </div>
 </div>
@@ -772,12 +772,12 @@ <h3 class="callout-title">Spot the Difference<a class="anchor" aria-label="ancho
 </ol><div class="codewrapper sourceCode" id="cb29">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a>easy_string <span class="op">=</span> <span class="st">"abc"</span></span>
-<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span>
-<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a>rich <span class="op">=</span> <span class="st">"gold"</span></span>
-<span id="cb29-4"><a href="#cb29-4" aria-hidden="true" tabindex="-1"></a>poor <span class="op">=</span> <span class="st">"tin"</span></span>
-<span id="cb29-5"><a href="#cb29-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span>
-<span id="cb29-6"><a href="#cb29-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" tabindex="-1"></a>easy_string <span class="op">=</span> <span class="st">"abc"</span></span>
+<span id="cb29-2"><a href="#cb29-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span>
+<span id="cb29-3"><a href="#cb29-3" tabindex="-1"></a>rich <span class="op">=</span> <span class="st">"gold"</span></span>
+<span id="cb29-4"><a href="#cb29-4" tabindex="-1"></a>poor <span class="op">=</span> <span class="st">"tin"</span></span>
+<span id="cb29-5"><a href="#cb29-5" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span>
+<span id="cb29-6"><a href="#cb29-6" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
 </div>
 </div>
 </div>
@@ -792,7 +792,7 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -802,7 +802,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -812,7 +812,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -891,13 +891,12 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </div>
 </div>
 </div>
-<div id="explore-the-python-docs" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="explore-the-python-docs" class="callout-inner">
-<h3 class="callout-title">Explore the Python docs!<a class="anchor" aria-label="anchor" href="#explore-the-python-docs"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="explore-the-python-docs">Explore the Python docs!<a class="anchor" aria-label="anchor" href="#explore-the-python-docs"></a></h3>
 <div class="callout-content">
 <p>The <a href="https://docs.python.org/3/" class="external-link">official Python
 documentation</a> is arguably the most complete source of information
@@ -997,7 +996,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/04-built-in.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/05-coffee.html b/05-coffee.html
index 3ba68db63..541f2c820 100644
--- a/05-coffee.html
+++ b/05-coffee.html
@@ -463,7 +463,7 @@ <h1>Morning Coffee</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/05-coffee.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/06-libraries.html b/06-libraries.html
index a8edfaaae..953b2076b 100644
--- a/06-libraries.html
+++ b/06-libraries.html
@@ -448,13 +448,12 @@ <h3 class="card-title">Objectives</h3>
 <li>Many additional libraries are available from <a href="https://pypi.python.org/pypi/" class="external-link">PyPI</a> (the Python Package
 Index).</li>
 <li>We will see later how to write new libraries.</li>
-</ul><div id="libraries-and-modules" class="callout callout">
+</ul><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="libraries-and-modules" class="callout-inner">
-<h3 class="callout-title">Libraries and modules<a class="anchor" aria-label="anchor" href="#libraries-and-modules"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="libraries-and-modules">Libraries and modules<a class="anchor" aria-label="anchor" href="#libraries-and-modules"></a></h3>
 <div class="callout-content">
 <p>A library is a collection of modules, but the terms are often used
 interchangeably, especially since many libraries only consist of a
@@ -475,10 +474,10 @@ <h3 class="callout-title">Libraries and modules<a class="anchor" aria-label="anc
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pi is'</span>, math.pi)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, math.cos(math.pi))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> math</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pi is'</span>, math.pi)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, math.cos(math.pi))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -499,7 +498,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(math)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="bu">help</span>(math)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -536,9 +535,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> cos, pi</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, cos(pi))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> cos, pi</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a></span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, cos(pi))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -554,9 +553,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, m.cos(m.pi))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a></span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, m.cos(m.pi))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -619,7 +618,7 @@ <h3 class="callout-title">Locating the Right Module<a class="anchor" aria-label=
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">'ACTTGCTTGAC'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">'ACTTGCTTGAC'</span></span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>Which <a href="https://docs.python.org/3/library/" class="external-link">standard
 library</a> module could help you?</li>
@@ -646,18 +645,18 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>random_index <span class="op">=</span> randrange(<span class="bu">len</span>(bases))</span>
-<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(bases[random_index])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a></span>
+<span id="cb10-3"><a href="#cb10-3" tabindex="-1"></a>random_index <span class="op">=</span> randrange(<span class="bu">len</span>(bases))</span>
+<span id="cb10-4"><a href="#cb10-4" tabindex="-1"></a><span class="bu">print</span>(bases[random_index])</span></code></pre>
 </div>
 <p>or more compactly:</p>
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(bases[randrange(<span class="bu">len</span>(bases))])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a></span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a><span class="bu">print</span>(bases[randrange(<span class="bu">len</span>(bases))])</span></code></pre>
 </div>
 <p>Perhaps you found the <a href="https://docs.python.org/3/library/random.html#random.sample" class="external-link"><code>random.sample</code></a>
 function? It allows for slightly less typing but might be a bit harder
@@ -665,9 +664,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> sample</span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(sample(bases, <span class="dv">1</span>)[<span class="dv">0</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> sample</span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a></span>
+<span id="cb12-3"><a href="#cb12-3" tabindex="-1"></a><span class="bu">print</span>(sample(bases, <span class="dv">1</span>)[<span class="dv">0</span>])</span></code></pre>
 </div>
 <p>Note that this function returns a list of values. We will learn about
 lists in <a href="11-lists.html">episode 11</a>.</p>
@@ -676,9 +675,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> choice</span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(choice(bases))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> choice</span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a></span>
+<span id="cb13-3"><a href="#cb13-3" tabindex="-1"></a><span class="bu">print</span>(choice(bases))</span></code></pre>
 </div>
 </div>
 </div>
@@ -699,12 +698,12 @@ <h3 class="callout-title">Jigsaw Puzzle (Parson’s Problem) Programming
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>bases<span class="op">=</span><span class="st">"ACTTGCTTGAC"</span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math</span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a>___ <span class="op">=</span> random.randrange(n_bases)</span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a>___ <span class="op">=</span> <span class="bu">len</span>(bases)</span>
-<span id="cb14-6"><a href="#cb14-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base "</span>, bases[___], <span class="st">"base index"</span>, ___)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>bases<span class="op">=</span><span class="st">"ACTTGCTTGAC"</span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a><span class="im">import</span> math</span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a>___ <span class="op">=</span> random.randrange(n_bases)</span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a>___ <span class="op">=</span> <span class="bu">len</span>(bases)</span>
+<span id="cb14-6"><a href="#cb14-6" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base "</span>, bases[___], <span class="st">"base index"</span>, ___)</span></code></pre>
 </div>
 </div>
 </div>
@@ -719,12 +718,12 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math </span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">"ACTTGCTTGAC"</span> </span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a>n_bases <span class="op">=</span> <span class="bu">len</span>(bases)</span>
-<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a>idx <span class="op">=</span> random.randrange(n_bases)</span>
-<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base"</span>, bases[idx], <span class="st">"base index"</span>, idx)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="im">import</span> math </span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">"ACTTGCTTGAC"</span> </span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a>n_bases <span class="op">=</span> <span class="bu">len</span>(bases)</span>
+<span id="cb15-5"><a href="#cb15-5" tabindex="-1"></a>idx <span class="op">=</span> random.randrange(n_bases)</span>
+<span id="cb15-6"><a href="#cb15-6" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base"</span>, bases[idx], <span class="st">"base index"</span>, idx)</span></code></pre>
 </div>
 </div>
 </div>
@@ -777,9 +776,9 @@ <h3 class="callout-title">Importing With Aliases<a class="anchor" aria-label="an
 </ol><div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> ____.degrees(____.pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(____)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>angle <span class="op">=</span> ____.degrees(____.pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a><span class="bu">print</span>(____)</span></code></pre>
 </div>
 </div>
 </div>
@@ -794,17 +793,17 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
-<span id="cb18-2"><a href="#cb18-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> m.degrees(m.pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb18-3"><a href="#cb18-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
+<span id="cb18-2"><a href="#cb18-2" tabindex="-1"></a>angle <span class="op">=</span> m.degrees(m.pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb18-3"><a href="#cb18-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 <p>can be written as</p>
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> math.degrees(math.pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="im">import</span> math</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>angle <span class="op">=</span> math.degrees(math.pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 <p>Since you just wrote the code and are familiar with it, you might
 actually find the first version easier to read. But when trying to read
@@ -887,9 +886,9 @@ <h3 class="callout-title">Importing Specific Items<a class="anchor" aria-label="
 </ol><div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>____ math <span class="im">import</span> ____, ____</span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>____ math <span class="im">import</span> ____, ____</span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 </div>
 </div>
@@ -904,9 +903,9 @@ <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> degrees, pi</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> degrees, pi</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 <p>Most likely you find this version easier to read since it’s less
 dense. The main reason not to use this form of import is to avoid name
@@ -933,8 +932,8 @@ <h3 class="callout-title">Reading Error Messages<a class="anchor" aria-label="an
 </ol><div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> log</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>log(<span class="dv">0</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> log</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>log(<span class="dv">0</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -1044,7 +1043,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/06-libraries.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/07-reading-tabular.html b/07-reading-tabular.html
index 6a6c12442..7f843d107 100644
--- a/07-reading-tabular.html
+++ b/07-reading-tabular.html
@@ -449,10 +449,10 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>data_oceania <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>data_oceania <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a><span class="bu">print</span>(data_oceania)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -480,13 +480,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <li>Using descriptive dataframe names helps us distinguish between
 multiple dataframes so we won’t accidentally overwrite a dataframe or
 read from the wrong one.</li>
-</ul><div id="file-not-found" class="callout callout">
+</ul><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="file-not-found" class="callout-inner">
-<h3 class="callout-title">File Not Found<a class="anchor" aria-label="anchor" href="#file-not-found"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="file-not-found">File Not Found<a class="anchor" aria-label="anchor" href="#file-not-found"></a></h3>
 <div class="callout-content">
 <p>Our lessons store their data files in a <code>data</code>
 sub-directory, which is why the path to the file is
@@ -515,8 +514,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>data_oceania_country <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a>data_oceania_country <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -542,7 +541,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>data_oceania_country.info()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a>data_oceania_country.info()</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -588,7 +587,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.columns)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.columns)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -607,7 +606,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.T)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.T)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -635,7 +634,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.describe())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.describe())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -692,7 +691,7 @@ <h3 class="callout-title">Reading Other Data<a class="anchor" aria-label="anchor
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>To read in a CSV, we use <code>pd.read_csv</code> and pass the
 filename <code>'data/gapminder_gdp_americas.csv'</code> to it. We also
@@ -703,8 +702,8 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>data_americas <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_americas.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a>data_americas.describe()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>data_americas <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_americas.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a>data_americas.describe()</span></code></pre>
 </div>
 </div>
 </div>
@@ -734,7 +733,7 @@ <h3 class="callout-title">Inspecting Data<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <ol style="list-style-type: decimal"><li>We can check out the first five rows of <code>data_americas</code>
 by executing <code>data_americas.head()</code> which lets us view the
@@ -745,7 +744,7 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </ol><div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>data_americas.head(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a>data_americas.head(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -783,14 +782,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ol><div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>americas_flipped <span class="op">=</span> data_americas.T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>americas_flipped <span class="op">=</span> data_americas.T</span></code></pre>
 </div>
 <p>We can then view the last three columns of <code>americas</code> by
 viewing the last three rows of <code>americas_flipped</code>:</p>
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -820,14 +819,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>).T    </span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>).T    </span></code></pre>
 </div>
 <p><strong>Note:</strong> we could have done the above in a single line
 of code by ‘chaining’ the commands:</p>
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a>data_americas.T.tail(n<span class="op">=</span><span class="dv">3</span>).T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a>data_americas.T.tail(n<span class="op">=</span><span class="dv">3</span>).T</span></code></pre>
 </div>
 </div>
 </div>
@@ -865,7 +864,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>We need to specify the path to the file of interest in the call to
 <code>pd.read_csv</code>. We first need to ‘jump’ out of the folder
@@ -875,7 +874,7 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a>data_microbes <span class="op">=</span> pd.read_csv(<span class="st">'../field_data/microbes.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a>data_microbes <span class="op">=</span> pd.read_csv(<span class="st">'../field_data/microbes.csv'</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -903,22 +902,22 @@ <h3 class="callout-title">Writing Data<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>In order to write the DataFrame <code>data_americas</code> to a file
 called <code>processed.csv</code>, execute the following command:</p>
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a>data_americas.to_csv(<span class="st">'processed.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a>data_americas.to_csv(<span class="st">'processed.csv'</span>)</span></code></pre>
 </div>
 <p>For help on <code>read_csv</code> or <code>to_csv</code>, you could
 execute, for example:</p>
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(data_americas.to_csv)</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(pd.read_csv)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="bu">help</span>(data_americas.to_csv)</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a><span class="bu">help</span>(pd.read_csv)</span></code></pre>
 </div>
 <p>Note that <code>help(to_csv)</code> or <code>help(pd.to_csv)</code>
 throws an error! This is due to the fact that <code>to_csv</code> is not
@@ -1011,7 +1010,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/07-reading-tabular.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/08-data-frames.html b/08-data-frames.html
index b40f51a7d..d63daf68b 100644
--- a/08-data-frames.html
+++ b/08-data-frames.html
@@ -462,9 +462,9 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.iloc[<span class="dv">0</span>, <span class="dv">0</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="bu">print</span>(data.iloc[<span class="dv">0</span>, <span class="dv">0</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -478,7 +478,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -491,7 +491,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, :])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, :])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -515,7 +515,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[:, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[:, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -542,7 +542,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -568,7 +568,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">max</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">max</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -581,7 +581,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">min</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">min</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -599,12 +599,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Use a subset of data to keep output readable.</span></span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>subset <span class="op">=</span> data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>]</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Subset of data:</span><span class="ch">\n</span><span class="st">'</span>, subset)</span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Which values were greater than 10000 ?</span></span>
-<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'</span><span class="ch">\n</span><span class="st">Where are values large?</span><span class="ch">\n</span><span class="st">'</span>, subset <span class="op">&gt;</span> <span class="dv">10000</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="co"># Use a subset of data to keep output readable.</span></span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>subset <span class="op">=</span> data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>]</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Subset of data:</span><span class="ch">\n</span><span class="st">'</span>, subset)</span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a></span>
+<span id="cb15-5"><a href="#cb15-5" tabindex="-1"></a><span class="co"># Which values were greater than 10000 ?</span></span>
+<span id="cb15-6"><a href="#cb15-6" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'</span><span class="ch">\n</span><span class="st">Where are values large?</span><span class="ch">\n</span><span class="st">'</span>, subset <span class="op">&gt;</span> <span class="dv">10000</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -634,8 +634,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>mask <span class="op">=</span> subset <span class="op">&gt;</span> <span class="dv">10000</span></span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(subset[mask])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>mask <span class="op">=</span> subset <span class="op">&gt;</span> <span class="dv">10000</span></span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a><span class="bu">print</span>(subset[mask])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -655,7 +655,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(subset[subset <span class="op">&gt;</span> <span class="dv">10000</span>].describe())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="bu">print</span>(subset[subset <span class="op">&gt;</span> <span class="dv">10000</span>].describe())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -686,9 +686,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ol><div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a>mask_higher <span class="op">=</span> data <span class="op">&gt;</span> data.mean()</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a>wealth_score <span class="op">=</span> mask_higher.aggregate(<span class="st">'sum'</span>, axis<span class="op">=</span><span class="dv">1</span>) <span class="op">/</span> <span class="bu">len</span>(data.columns)</span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(wealth_score)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a>mask_higher <span class="op">=</span> data <span class="op">&gt;</span> data.mean()</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a>wealth_score <span class="op">=</span> mask_higher.aggregate(<span class="st">'sum'</span>, axis<span class="op">=</span><span class="dv">1</span>) <span class="op">/</span> <span class="bu">len</span>(data.columns)</span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="bu">print</span>(wealth_score)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -732,7 +732,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.groupby(wealth_score).<span class="bu">sum</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="bu">print</span>(data.groupby(wealth_score).<span class="bu">sum</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -768,9 +768,9 @@ <h3 class="callout-title">Selection of Individual Values<a class="anchor" aria-l
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a></span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
 </div>
 <p>Write an expression to find the Per Capita GDP of Serbia in 2007.</p>
 </div>
@@ -781,14 +781,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The selection can be done by using the labels for both the row
 (“Serbia”) and the column (“gdpPercap_2007”):</p>
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Serbia'</span>, <span class="st">'gdpPercap_2007'</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Serbia'</span>, <span class="st">'gdpPercap_2007'</span>])</span></code></pre>
 </div>
 <p>The output is</p>
 <div class="codewrapper">
@@ -814,8 +814,8 @@ <h3 class="callout-title">Extent of Slicing<a class="anchor" aria-label="anchor"
 </ol><div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_europe.iloc[<span class="dv">0</span>:<span class="dv">2</span>, <span class="dv">0</span>:<span class="dv">2</span>])</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Albania'</span>:<span class="st">'Belgium'</span>, <span class="st">'gdpPercap_1952'</span>:<span class="st">'gdpPercap_1962'</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a><span class="bu">print</span>(data_europe.iloc[<span class="dv">0</span>:<span class="dv">2</span>, <span class="dv">0</span>:<span class="dv">2</span>])</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Albania'</span>:<span class="st">'Belgium'</span>, <span class="st">'gdpPercap_1952'</span>:<span class="st">'gdpPercap_1962'</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -825,7 +825,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>No, they do not produce the same output! The output of the first
 statement is:</p>
@@ -870,11 +870,11 @@ <h3 class="callout-title">Reconstructing Data<a class="anchor" aria-label="ancho
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span>
-<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span>
-<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span>
-<span id="cb31-5"><a href="#cb31-5" aria-hidden="true" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span>
+<span id="cb31-3"><a href="#cb31-3" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span>
+<span id="cb31-4"><a href="#cb31-4" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span>
+<span id="cb31-5"><a href="#cb31-5" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -884,13 +884,13 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Let’s go through this piece of code line by line.</p>
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
 </div>
 <p>This line loads the dataset containing the GDP data from all
 countries into a dataframe called <code>first</code>. The
@@ -899,7 +899,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb33">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span></code></pre>
 </div>
 <p>This line makes a selection: only those rows of <code>first</code>
 for which the ‘continent’ column matches ‘Americas’ are extracted.
@@ -911,7 +911,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span></code></pre>
 </div>
 <p>As the syntax suggests, this line drops the row from
 <code>second</code> where the label is ‘Puerto Rico’. The resulting
@@ -920,7 +920,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span></code></pre>
 </div>
 <p>Again we apply the drop function, but in this case we are dropping
 not a row but a whole column. To accomplish this, we need to specify
@@ -929,7 +929,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb36">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" aria-hidden="true" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
 </div>
 <p>The final step is to write the data that we have been working on to a
 csv file. Pandas makes this easy with the <code>to_csv()</code>
@@ -954,9 +954,9 @@ <h3 class="callout-title">Selecting Indices<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb37-2"><a href="#cb37-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.idxmin())</span>
-<span id="cb37-3"><a href="#cb37-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.idxmax())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb37-2"><a href="#cb37-2" tabindex="-1"></a><span class="bu">print</span>(data.idxmin())</span>
+<span id="cb37-3"><a href="#cb37-3" tabindex="-1"></a><span class="bu">print</span>(data.idxmax())</span></code></pre>
 </div>
 </div>
 </div>
@@ -966,7 +966,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>For each column in <code>data</code>, <code>idxmin</code> will return
 the index value corresponding to each column’s minimum;
@@ -1002,25 +1002,25 @@ <h3 class="callout-title">Practice with Selection<a class="anchor" aria-label="a
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>1:</p>
 <div class="codewrapper sourceCode" id="cb38">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a>data[<span class="st">'gdpPercap_1982'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" tabindex="-1"></a>data[<span class="st">'gdpPercap_1982'</span>]</span></code></pre>
 </div>
 <p>2:</p>
 <div class="codewrapper sourceCode" id="cb39">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">'Denmark'</span>,:]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" tabindex="-1"></a>data.loc[<span class="st">'Denmark'</span>,:]</span></code></pre>
 </div>
 <p>3:</p>
 <div class="codewrapper sourceCode" id="cb40">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a>data.loc[:,<span class="st">'gdpPercap_1985'</span>:]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" tabindex="-1"></a>data.loc[:,<span class="st">'gdpPercap_1985'</span>:]</span></code></pre>
 </div>
 <p>Pandas is smart enough to recognize the number at the end of the
 column label and does not give you an error, although no column named
@@ -1030,7 +1030,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb41">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" aria-hidden="true" tabindex="-1"></a>data[<span class="st">'gdpPercap_2007'</span>]<span class="op">/</span>data[<span class="st">'gdpPercap_1952'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" tabindex="-1"></a>data[<span class="st">'gdpPercap_2007'</span>]<span class="op">/</span>data[<span class="st">'gdpPercap_1952'</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -1065,141 +1065,141 @@ <h3 class="callout-title">Many Ways of Access<a class="anchor" aria-label="ancho
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Show me the solution</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <p>1. Access a single column:</p>
 <div class="codewrapper sourceCode" id="cb42">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb42-2"><a href="#cb42-2" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"col_name"</span>]   <span class="co"># as a Series</span></span>
-<span id="cb42-3"><a href="#cb42-3" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]] <span class="co"># as a DataFrame</span></span>
-<span id="cb42-4"><a href="#cb42-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-5"><a href="#cb42-5" aria-hidden="true" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
-<span id="cb42-6"><a href="#cb42-6" aria-hidden="true" tabindex="-1"></a>data.T.loc[<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb42-7"><a href="#cb42-7" aria-hidden="true" tabindex="-1"></a>data.T.loc[[<span class="st">"col_name"</span>]].T  <span class="co"># as a DataFrame</span></span>
-<span id="cb42-8"><a href="#cb42-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-9"><a href="#cb42-9" aria-hidden="true" tabindex="-1"></a><span class="co"># Dot notation (Series)</span></span>
-<span id="cb42-10"><a href="#cb42-10" aria-hidden="true" tabindex="-1"></a>data.col_name</span>
-<span id="cb42-11"><a href="#cb42-11" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-12"><a href="#cb42-12" aria-hidden="true" tabindex="-1"></a><span class="co"># by index (iloc)</span></span>
-<span id="cb42-13"><a href="#cb42-13" aria-hidden="true" tabindex="-1"></a>data.iloc[:, col_index]   <span class="co"># as a Series</span></span>
-<span id="cb42-14"><a href="#cb42-14" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col_index]] <span class="co"># as a DataFrame</span></span>
-<span id="cb42-15"><a href="#cb42-15" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-16"><a href="#cb42-16" aria-hidden="true" tabindex="-1"></a><span class="co"># using a mask</span></span>
-<span id="cb42-17"><a href="#cb42-17" aria-hidden="true" tabindex="-1"></a>data.T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb42-2"><a href="#cb42-2" tabindex="-1"></a>data[<span class="st">"col_name"</span>]   <span class="co"># as a Series</span></span>
+<span id="cb42-3"><a href="#cb42-3" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]] <span class="co"># as a DataFrame</span></span>
+<span id="cb42-4"><a href="#cb42-4" tabindex="-1"></a></span>
+<span id="cb42-5"><a href="#cb42-5" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
+<span id="cb42-6"><a href="#cb42-6" tabindex="-1"></a>data.T.loc[<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb42-7"><a href="#cb42-7" tabindex="-1"></a>data.T.loc[[<span class="st">"col_name"</span>]].T  <span class="co"># as a DataFrame</span></span>
+<span id="cb42-8"><a href="#cb42-8" tabindex="-1"></a></span>
+<span id="cb42-9"><a href="#cb42-9" tabindex="-1"></a><span class="co"># Dot notation (Series)</span></span>
+<span id="cb42-10"><a href="#cb42-10" tabindex="-1"></a>data.col_name</span>
+<span id="cb42-11"><a href="#cb42-11" tabindex="-1"></a></span>
+<span id="cb42-12"><a href="#cb42-12" tabindex="-1"></a><span class="co"># by index (iloc)</span></span>
+<span id="cb42-13"><a href="#cb42-13" tabindex="-1"></a>data.iloc[:, col_index]   <span class="co"># as a Series</span></span>
+<span id="cb42-14"><a href="#cb42-14" tabindex="-1"></a>data.iloc[:, [col_index]] <span class="co"># as a DataFrame</span></span>
+<span id="cb42-15"><a href="#cb42-15" tabindex="-1"></a></span>
+<span id="cb42-16"><a href="#cb42-16" tabindex="-1"></a><span class="co"># using a mask</span></span>
+<span id="cb42-17"><a href="#cb42-17" tabindex="-1"></a>data.T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
 </div>
 <p>2. Access a single row:</p>
 <div class="codewrapper sourceCode" id="cb43">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
-<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
-<span id="cb43-3"><a href="#cb43-3" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]] <span class="co"># as a DataFrame</span></span>
-<span id="cb43-4"><a href="#cb43-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb43-5"><a href="#cb43-5" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb43-6"><a href="#cb43-6" aria-hidden="true" tabindex="-1"></a>data.T[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
-<span id="cb43-7"><a href="#cb43-7" aria-hidden="true" tabindex="-1"></a>data.T[[<span class="st">"row_name"</span>]].T <span class="co"># as a DataFrame</span></span>
-<span id="cb43-8"><a href="#cb43-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb43-9"><a href="#cb43-9" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb43-10"><a href="#cb43-10" aria-hidden="true" tabindex="-1"></a>data.iloc[row_index]   <span class="co"># as a Series</span></span>
-<span id="cb43-11"><a href="#cb43-11" aria-hidden="true" tabindex="-1"></a>data.iloc[[row_index]]   <span class="co"># as a DataFrame</span></span>
-<span id="cb43-12"><a href="#cb43-12" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb43-13"><a href="#cb43-13" aria-hidden="true" tabindex="-1"></a><span class="co"># using mask</span></span>
-<span id="cb43-14"><a href="#cb43-14" aria-hidden="true" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
+<span id="cb43-2"><a href="#cb43-2" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
+<span id="cb43-3"><a href="#cb43-3" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]] <span class="co"># as a DataFrame</span></span>
+<span id="cb43-4"><a href="#cb43-4" tabindex="-1"></a></span>
+<span id="cb43-5"><a href="#cb43-5" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb43-6"><a href="#cb43-6" tabindex="-1"></a>data.T[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
+<span id="cb43-7"><a href="#cb43-7" tabindex="-1"></a>data.T[[<span class="st">"row_name"</span>]].T <span class="co"># as a DataFrame</span></span>
+<span id="cb43-8"><a href="#cb43-8" tabindex="-1"></a></span>
+<span id="cb43-9"><a href="#cb43-9" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb43-10"><a href="#cb43-10" tabindex="-1"></a>data.iloc[row_index]   <span class="co"># as a Series</span></span>
+<span id="cb43-11"><a href="#cb43-11" tabindex="-1"></a>data.iloc[[row_index]]   <span class="co"># as a DataFrame</span></span>
+<span id="cb43-12"><a href="#cb43-12" tabindex="-1"></a></span>
+<span id="cb43-13"><a href="#cb43-13" tabindex="-1"></a><span class="co"># using mask</span></span>
+<span id="cb43-14"><a href="#cb43-14" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>]</span></code></pre>
 </div>
 <p>3. Access an individual DataFrame element:</p>
 <div class="codewrapper sourceCode" id="cb44">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by column/row names</span></span>
-<span id="cb44-2"><a href="#cb44-2" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"column_name"</span>][<span class="st">"row_name"</span>]         <span class="co"># as a Series</span></span>
-<span id="cb44-3"><a href="#cb44-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-4"><a href="#cb44-4" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb44-5"><a href="#cb44-5" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
-<span id="cb44-6"><a href="#cb44-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-7"><a href="#cb44-7" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>][<span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
-<span id="cb44-8"><a href="#cb44-8" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb44-9"><a href="#cb44-9" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][[<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame</span></span>
-<span id="cb44-10"><a href="#cb44-10" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-11"><a href="#cb44-11" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, <span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
-<span id="cb44-12"><a href="#cb44-12" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], <span class="st">"col_name"</span>]  <span class="co"># as a Series. Preserves index. Column name is moved to `.name`.</span></span>
-<span id="cb44-13"><a href="#cb44-13" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, [<span class="st">"col_name"</span>]]  <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
-<span id="cb44-14"><a href="#cb44-14" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], [<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
-<span id="cb44-15"><a href="#cb44-15" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-16"><a href="#cb44-16" aria-hidden="true" tabindex="-1"></a><span class="co"># by column/row names: Dot notation</span></span>
-<span id="cb44-17"><a href="#cb44-17" aria-hidden="true" tabindex="-1"></a>data.col_name.row_name</span>
-<span id="cb44-18"><a href="#cb44-18" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-19"><a href="#cb44-19" aria-hidden="true" tabindex="-1"></a><span class="co"># by column/row indices</span></span>
-<span id="cb44-20"><a href="#cb44-20" aria-hidden="true" tabindex="-1"></a>data.iloc[row_index, col_index] <span class="co"># as a value</span></span>
-<span id="cb44-21"><a href="#cb44-21" aria-hidden="true" tabindex="-1"></a>data.iloc[[row_index], col_index] <span class="co"># as a Series. Preserves index. Column name is moved to `.name`</span></span>
-<span id="cb44-22"><a href="#cb44-22" aria-hidden="true" tabindex="-1"></a>data.iloc[row_index, [col_index]] <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
-<span id="cb44-23"><a href="#cb44-23" aria-hidden="true" tabindex="-1"></a>data.iloc[[row_index], [col_index]] <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
-<span id="cb44-24"><a href="#cb44-24" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-25"><a href="#cb44-25" aria-hidden="true" tabindex="-1"></a><span class="co"># column name + row index</span></span>
-<span id="cb44-26"><a href="#cb44-26" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"col_name"</span>][row_index]</span>
-<span id="cb44-27"><a href="#cb44-27" aria-hidden="true" tabindex="-1"></a>data.col_name[row_index]</span>
-<span id="cb44-28"><a href="#cb44-28" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"col_name"</span>].iloc[row_index]</span>
-<span id="cb44-29"><a href="#cb44-29" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-30"><a href="#cb44-30" aria-hidden="true" tabindex="-1"></a><span class="co"># column index + row name</span></span>
-<span id="cb44-31"><a href="#cb44-31" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col_index]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb44-32"><a href="#cb44-32" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col_index]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
-<span id="cb44-33"><a href="#cb44-33" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-34"><a href="#cb44-34" aria-hidden="true" tabindex="-1"></a><span class="co"># using masks</span></span>
-<span id="cb44-35"><a href="#cb44-35" aria-hidden="true" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>].T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" tabindex="-1"></a><span class="co"># by column/row names</span></span>
+<span id="cb44-2"><a href="#cb44-2" tabindex="-1"></a>data[<span class="st">"column_name"</span>][<span class="st">"row_name"</span>]         <span class="co"># as a Series</span></span>
+<span id="cb44-3"><a href="#cb44-3" tabindex="-1"></a></span>
+<span id="cb44-4"><a href="#cb44-4" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb44-5"><a href="#cb44-5" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
+<span id="cb44-6"><a href="#cb44-6" tabindex="-1"></a></span>
+<span id="cb44-7"><a href="#cb44-7" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>][<span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
+<span id="cb44-8"><a href="#cb44-8" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb44-9"><a href="#cb44-9" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][[<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame</span></span>
+<span id="cb44-10"><a href="#cb44-10" tabindex="-1"></a></span>
+<span id="cb44-11"><a href="#cb44-11" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, <span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
+<span id="cb44-12"><a href="#cb44-12" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], <span class="st">"col_name"</span>]  <span class="co"># as a Series. Preserves index. Column name is moved to `.name`.</span></span>
+<span id="cb44-13"><a href="#cb44-13" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, [<span class="st">"col_name"</span>]]  <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
+<span id="cb44-14"><a href="#cb44-14" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], [<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
+<span id="cb44-15"><a href="#cb44-15" tabindex="-1"></a></span>
+<span id="cb44-16"><a href="#cb44-16" tabindex="-1"></a><span class="co"># by column/row names: Dot notation</span></span>
+<span id="cb44-17"><a href="#cb44-17" tabindex="-1"></a>data.col_name.row_name</span>
+<span id="cb44-18"><a href="#cb44-18" tabindex="-1"></a></span>
+<span id="cb44-19"><a href="#cb44-19" tabindex="-1"></a><span class="co"># by column/row indices</span></span>
+<span id="cb44-20"><a href="#cb44-20" tabindex="-1"></a>data.iloc[row_index, col_index] <span class="co"># as a value</span></span>
+<span id="cb44-21"><a href="#cb44-21" tabindex="-1"></a>data.iloc[[row_index], col_index] <span class="co"># as a Series. Preserves index. Column name is moved to `.name`</span></span>
+<span id="cb44-22"><a href="#cb44-22" tabindex="-1"></a>data.iloc[row_index, [col_index]] <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
+<span id="cb44-23"><a href="#cb44-23" tabindex="-1"></a>data.iloc[[row_index], [col_index]] <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
+<span id="cb44-24"><a href="#cb44-24" tabindex="-1"></a></span>
+<span id="cb44-25"><a href="#cb44-25" tabindex="-1"></a><span class="co"># column name + row index</span></span>
+<span id="cb44-26"><a href="#cb44-26" tabindex="-1"></a>data[<span class="st">"col_name"</span>][row_index]</span>
+<span id="cb44-27"><a href="#cb44-27" tabindex="-1"></a>data.col_name[row_index]</span>
+<span id="cb44-28"><a href="#cb44-28" tabindex="-1"></a>data[<span class="st">"col_name"</span>].iloc[row_index]</span>
+<span id="cb44-29"><a href="#cb44-29" tabindex="-1"></a></span>
+<span id="cb44-30"><a href="#cb44-30" tabindex="-1"></a><span class="co"># column index + row name</span></span>
+<span id="cb44-31"><a href="#cb44-31" tabindex="-1"></a>data.iloc[:, [col_index]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb44-32"><a href="#cb44-32" tabindex="-1"></a>data.iloc[:, [col_index]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
+<span id="cb44-33"><a href="#cb44-33" tabindex="-1"></a></span>
+<span id="cb44-34"><a href="#cb44-34" tabindex="-1"></a><span class="co"># using masks</span></span>
+<span id="cb44-35"><a href="#cb44-35" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>].T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
 </div>
 <p>4. Access several columns:</p>
 <div class="codewrapper sourceCode" id="cb45">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb45-1"><a href="#cb45-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb45-2"><a href="#cb45-2" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
-<span id="cb45-3"><a href="#cb45-3" aria-hidden="true" tabindex="-1"></a>data.loc[:, [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
-<span id="cb45-4"><a href="#cb45-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb45-5"><a href="#cb45-5" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb45-6"><a href="#cb45-6" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb45-1"><a href="#cb45-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb45-2"><a href="#cb45-2" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
+<span id="cb45-3"><a href="#cb45-3" tabindex="-1"></a>data.loc[:, [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
+<span id="cb45-4"><a href="#cb45-4" tabindex="-1"></a></span>
+<span id="cb45-5"><a href="#cb45-5" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb45-6"><a href="#cb45-6" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]]</span></code></pre>
 </div>
 <p>5. Access several rows</p>
 <div class="codewrapper sourceCode" id="cb46">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb46-2"><a href="#cb46-2" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span>
-<span id="cb46-3"><a href="#cb46-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb46-4"><a href="#cb46-4" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb46-5"><a href="#cb46-5" aria-hidden="true" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index]]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb46-2"><a href="#cb46-2" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span>
+<span id="cb46-3"><a href="#cb46-3" tabindex="-1"></a></span>
+<span id="cb46-4"><a href="#cb46-4" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb46-5"><a href="#cb46-5" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index]]</span></code></pre>
 </div>
 <p>6. Access a subset of specific rows and columns</p>
 <div class="codewrapper sourceCode" id="cb47">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb47-1"><a href="#cb47-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by names</span></span>
-<span id="cb47-2"><a href="#cb47-2" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>], [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
-<span id="cb47-3"><a href="#cb47-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb47-4"><a href="#cb47-4" aria-hidden="true" tabindex="-1"></a><span class="co"># by indices</span></span>
-<span id="cb47-5"><a href="#cb47-5" aria-hidden="true" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index], [col1_index, col2_index, col3_index]]</span>
-<span id="cb47-6"><a href="#cb47-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb47-7"><a href="#cb47-7" aria-hidden="true" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
-<span id="cb47-8"><a href="#cb47-8" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]].iloc[[row1_index, row2_index, row3_index]]</span>
-<span id="cb47-9"><a href="#cb47-9" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb47-10"><a href="#cb47-10" aria-hidden="true" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
-<span id="cb47-11"><a href="#cb47-11" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]].loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb47-1"><a href="#cb47-1" tabindex="-1"></a><span class="co"># by names</span></span>
+<span id="cb47-2"><a href="#cb47-2" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>], [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
+<span id="cb47-3"><a href="#cb47-3" tabindex="-1"></a></span>
+<span id="cb47-4"><a href="#cb47-4" tabindex="-1"></a><span class="co"># by indices</span></span>
+<span id="cb47-5"><a href="#cb47-5" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index], [col1_index, col2_index, col3_index]]</span>
+<span id="cb47-6"><a href="#cb47-6" tabindex="-1"></a></span>
+<span id="cb47-7"><a href="#cb47-7" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
+<span id="cb47-8"><a href="#cb47-8" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]].iloc[[row1_index, row2_index, row3_index]]</span>
+<span id="cb47-9"><a href="#cb47-9" tabindex="-1"></a></span>
+<span id="cb47-10"><a href="#cb47-10" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
+<span id="cb47-11"><a href="#cb47-11" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]].loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span></code></pre>
 </div>
 <p>7. Access a subset of row and column ranges</p>
 <div class="codewrapper sourceCode" id="cb48">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb48-2"><a href="#cb48-2" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>, <span class="st">"col1"</span>:<span class="st">"col2"</span>]</span>
-<span id="cb48-3"><a href="#cb48-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb48-4"><a href="#cb48-4" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb48-5"><a href="#cb48-5" aria-hidden="true" tabindex="-1"></a>data.iloc[row1_index:row2_index, col1_index:col2_index]</span>
-<span id="cb48-6"><a href="#cb48-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb48-7"><a href="#cb48-7" aria-hidden="true" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
-<span id="cb48-8"><a href="#cb48-8" aria-hidden="true" tabindex="-1"></a>data.loc[:, <span class="st">"col1_name"</span>:<span class="st">"col2_name"</span>].iloc[row1_index:row2_index]</span>
-<span id="cb48-9"><a href="#cb48-9" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb48-10"><a href="#cb48-10" aria-hidden="true" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
-<span id="cb48-11"><a href="#cb48-11" aria-hidden="true" tabindex="-1"></a>data.iloc[:, col1_index:col2_index].loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb48-2"><a href="#cb48-2" tabindex="-1"></a>data.loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>, <span class="st">"col1"</span>:<span class="st">"col2"</span>]</span>
+<span id="cb48-3"><a href="#cb48-3" tabindex="-1"></a></span>
+<span id="cb48-4"><a href="#cb48-4" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb48-5"><a href="#cb48-5" tabindex="-1"></a>data.iloc[row1_index:row2_index, col1_index:col2_index]</span>
+<span id="cb48-6"><a href="#cb48-6" tabindex="-1"></a></span>
+<span id="cb48-7"><a href="#cb48-7" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
+<span id="cb48-8"><a href="#cb48-8" tabindex="-1"></a>data.loc[:, <span class="st">"col1_name"</span>:<span class="st">"col2_name"</span>].iloc[row1_index:row2_index]</span>
+<span id="cb48-9"><a href="#cb48-9" tabindex="-1"></a></span>
+<span id="cb48-10"><a href="#cb48-10" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
+<span id="cb48-11"><a href="#cb48-11" tabindex="-1"></a>data.iloc[:, col1_index:col2_index].loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -1220,22 +1220,22 @@ <h3 class="callout-title">Exploring available methods using the<code>dir()</code
 <div class="codewrapper sourceCode" id="cb49">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb49-1"><a href="#cb49-1" aria-hidden="true" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>   <span class="co"># creation of a string object </span></span>
-<span id="cb49-2"><a href="#cb49-2" aria-hidden="true" tabindex="-1"></a><span class="bu">dir</span>(my_string)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb49-1"><a href="#cb49-1" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>   <span class="co"># creation of a string object </span></span>
+<span id="cb49-2"><a href="#cb49-2" tabindex="-1"></a><span class="bu">dir</span>(my_string)</span></code></pre>
 </div>
 <p>This command returns:</p>
 <div class="codewrapper sourceCode" id="cb50">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb50-1"><a href="#cb50-1" aria-hidden="true" tabindex="-1"></a>[<span class="st">'__add__'</span>,</span>
-<span id="cb50-2"><a href="#cb50-2" aria-hidden="true" tabindex="-1"></a>...</span>
-<span id="cb50-3"><a href="#cb50-3" aria-hidden="true" tabindex="-1"></a><span class="st">'__subclasshook__'</span>,</span>
-<span id="cb50-4"><a href="#cb50-4" aria-hidden="true" tabindex="-1"></a><span class="st">'capitalize'</span>,</span>
-<span id="cb50-5"><a href="#cb50-5" aria-hidden="true" tabindex="-1"></a><span class="st">'casefold'</span>,</span>
-<span id="cb50-6"><a href="#cb50-6" aria-hidden="true" tabindex="-1"></a><span class="st">'center'</span>,</span>
-<span id="cb50-7"><a href="#cb50-7" aria-hidden="true" tabindex="-1"></a>...</span>
-<span id="cb50-8"><a href="#cb50-8" aria-hidden="true" tabindex="-1"></a><span class="st">'upper'</span>,</span>
-<span id="cb50-9"><a href="#cb50-9" aria-hidden="true" tabindex="-1"></a><span class="st">'zfill'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb50-1"><a href="#cb50-1" tabindex="-1"></a>[<span class="st">'__add__'</span>,</span>
+<span id="cb50-2"><a href="#cb50-2" tabindex="-1"></a>...</span>
+<span id="cb50-3"><a href="#cb50-3" tabindex="-1"></a><span class="st">'__subclasshook__'</span>,</span>
+<span id="cb50-4"><a href="#cb50-4" tabindex="-1"></a><span class="st">'capitalize'</span>,</span>
+<span id="cb50-5"><a href="#cb50-5" tabindex="-1"></a><span class="st">'casefold'</span>,</span>
+<span id="cb50-6"><a href="#cb50-6" tabindex="-1"></a><span class="st">'center'</span>,</span>
+<span id="cb50-7"><a href="#cb50-7" tabindex="-1"></a>...</span>
+<span id="cb50-8"><a href="#cb50-8" tabindex="-1"></a><span class="st">'upper'</span>,</span>
+<span id="cb50-9"><a href="#cb50-9" tabindex="-1"></a><span class="st">'zfill'</span>]</span></code></pre>
 </div>
 <p>You can use <code>help()</code> or <kbd>Shift</kbd>+<kbd>Tab</kbd> to
 get more information about what these methods do.</p>
@@ -1251,14 +1251,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
 <div class="accordion-body">
 <p>Among many choices, <code>dir()</code> lists the
 <code>median()</code> function as a possibility. Thus,</p>
 <div class="codewrapper sourceCode" id="cb51">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb51-1"><a href="#cb51-1" aria-hidden="true" tabindex="-1"></a>data.median()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb51-1"><a href="#cb51-1" tabindex="-1"></a>data.median()</span></code></pre>
 </div>
 </div>
 </div>
@@ -1357,7 +1357,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/08-data-frames.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-08-29",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/09-plotting.html b/09-plotting.html
index 0e9772485..e2daf7a77 100644
--- a/09-plotting.html
+++ b/09-plotting.html
@@ -438,26 +438,25 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span></code></pre>
 </div>
 <ul><li>Simple plots are then (fairly) simple to create.</li>
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a>time <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>]</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>position <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">100</span>, <span class="dv">200</span>, <span class="dv">300</span>]</span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a>plt.plot(time, position)</span>
-<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a>plt.xlabel(<span class="st">'Time (hr)'</span>)</span>
-<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'Position (km)'</span>)</span></code></pre>
-</div>
-<figure><img src="fig/9_simple_position_time_plot.svg" alt="Simple Position-Time Plot" class="figure mx-auto d-block"></figure><div id="display-all-open-figures" class="callout callout">
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a>time <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>]</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a>position <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">100</span>, <span class="dv">200</span>, <span class="dv">300</span>]</span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a></span>
+<span id="cb2-4"><a href="#cb2-4" tabindex="-1"></a>plt.plot(time, position)</span>
+<span id="cb2-5"><a href="#cb2-5" tabindex="-1"></a>plt.xlabel(<span class="st">'Time (hr)'</span>)</span>
+<span id="cb2-6"><a href="#cb2-6" tabindex="-1"></a>plt.ylabel(<span class="st">'Position (km)'</span>)</span></code></pre>
+</div>
+<figure><img src="fig/9_simple_position_time_plot.svg" alt="Simple Position-Time Plot" class="figure mx-auto d-block"></figure><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="display-all-open-figures" class="callout-inner">
-<h3 class="callout-title">Display All Open Figures<a class="anchor" aria-label="anchor" href="#display-all-open-figures"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="display-all-open-figures">Display All Open Figures<a class="anchor" aria-label="anchor" href="#display-all-open-figures"></a></h3>
 <div class="callout-content">
 <p>In our Jupyter Notebook example, running the cell should generate the
 figure directly below the code. The figure is also included in the
@@ -469,7 +468,7 @@ <h3 class="callout-title">Display All Open Figures<a class="anchor" aria-label="
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>plt.show()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a>plt.show()</span></code></pre>
 </div>
 <p>This command can also be used within a Notebook - for instance, to
 display multiple figures if several are created by a single cell.</p>
@@ -490,23 +489,23 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-5"><a href="#cb4-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Extract year from last 4 characters of each column name</span></span>
-<span id="cb4-6"><a href="#cb4-6" aria-hidden="true" tabindex="-1"></a><span class="co"># The current column names are structured as 'gdpPercap_(year)', </span></span>
-<span id="cb4-7"><a href="#cb4-7" aria-hidden="true" tabindex="-1"></a><span class="co"># so we want to keep the (year) part only for clarity when plotting GDP vs. years</span></span>
-<span id="cb4-8"><a href="#cb4-8" aria-hidden="true" tabindex="-1"></a><span class="co"># To do this we use replace(), which removes from the string the characters stated in the argument</span></span>
-<span id="cb4-9"><a href="#cb4-9" aria-hidden="true" tabindex="-1"></a><span class="co"># This method works on strings, so we use replace() from Pandas Series.str vectorized string functions</span></span>
-<span id="cb4-10"><a href="#cb4-10" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-11"><a href="#cb4-11" aria-hidden="true" tabindex="-1"></a>years <span class="op">=</span> data.columns.<span class="bu">str</span>.replace(<span class="st">'gdpPercap_'</span>, <span class="st">''</span>)</span>
-<span id="cb4-12"><a href="#cb4-12" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-13"><a href="#cb4-13" aria-hidden="true" tabindex="-1"></a><span class="co"># Convert year values to integers, saving results back to dataframe</span></span>
-<span id="cb4-14"><a href="#cb4-14" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-15"><a href="#cb4-15" aria-hidden="true" tabindex="-1"></a>data.columns <span class="op">=</span> years.astype(<span class="bu">int</span>)</span>
-<span id="cb4-16"><a href="#cb4-16" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-17"><a href="#cb4-17" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">'Australia'</span>].plot()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a></span>
+<span id="cb4-3"><a href="#cb4-3" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb4-4"><a href="#cb4-4" tabindex="-1"></a></span>
+<span id="cb4-5"><a href="#cb4-5" tabindex="-1"></a><span class="co"># Extract year from last 4 characters of each column name</span></span>
+<span id="cb4-6"><a href="#cb4-6" tabindex="-1"></a><span class="co"># The current column names are structured as 'gdpPercap_(year)', </span></span>
+<span id="cb4-7"><a href="#cb4-7" tabindex="-1"></a><span class="co"># so we want to keep the (year) part only for clarity when plotting GDP vs. years</span></span>
+<span id="cb4-8"><a href="#cb4-8" tabindex="-1"></a><span class="co"># To do this we use replace(), which removes from the string the characters stated in the argument</span></span>
+<span id="cb4-9"><a href="#cb4-9" tabindex="-1"></a><span class="co"># This method works on strings, so we use replace() from Pandas Series.str vectorized string functions</span></span>
+<span id="cb4-10"><a href="#cb4-10" tabindex="-1"></a></span>
+<span id="cb4-11"><a href="#cb4-11" tabindex="-1"></a>years <span class="op">=</span> data.columns.<span class="bu">str</span>.replace(<span class="st">'gdpPercap_'</span>, <span class="st">''</span>)</span>
+<span id="cb4-12"><a href="#cb4-12" tabindex="-1"></a></span>
+<span id="cb4-13"><a href="#cb4-13" tabindex="-1"></a><span class="co"># Convert year values to integers, saving results back to dataframe</span></span>
+<span id="cb4-14"><a href="#cb4-14" tabindex="-1"></a></span>
+<span id="cb4-15"><a href="#cb4-15" tabindex="-1"></a>data.columns <span class="op">=</span> years.astype(<span class="bu">int</span>)</span>
+<span id="cb4-16"><a href="#cb4-16" tabindex="-1"></a></span>
+<span id="cb4-17"><a href="#cb4-17" tabindex="-1"></a>data.loc[<span class="st">'Australia'</span>].plot()</span></code></pre>
 </div>
 <figure><img src="fig/9_gdp_australia.svg" alt="GDP plot for Australia" class="figure mx-auto d-block"></figure></section><section id="select-and-transform-data-then-plot-it."><h2 class="section-heading">Select and transform data, then plot it.<a class="anchor" aria-label="anchor" href="#select-and-transform-data-then-plot-it."></a>
 </h2>
@@ -516,8 +515,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>data.T.plot()</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>data.T.plot()</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
 </div>
 <figure><img src="fig/9_gdp_australia_nz.svg" alt="GDP plot for Australia and New Zealand" class="figure mx-auto d-block"></figure></section><section id="many-styles-of-plot-are-available."><h2 class="section-heading">Many styles of plot are available.<a class="anchor" aria-label="anchor" href="#many-styles-of-plot-are-available."></a>
 </h2>
@@ -525,9 +524,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>plt.style.use(<span class="st">'ggplot'</span>)</span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a>data.T.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
-<span id="cb6-3"><a href="#cb6-3" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a>plt.style.use(<span class="st">'ggplot'</span>)</span>
+<span id="cb6-2"><a href="#cb6-2" tabindex="-1"></a>data.T.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
+<span id="cb6-3"><a href="#cb6-3" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
 </div>
 <figure><img src="fig/9_gdp_bar.svg" alt="GDP barplot for Australia" class="figure mx-auto d-block"></figure></section><section id="data-can-also-be-plotted-by-calling-the-matplotlib-plot-function-directly."><h2 class="section-heading">Data can also be plotted by calling the <code>matplotlib</code>
 <code>plot</code> function directly.<a class="anchor" aria-label="anchor" href="#data-can-also-be-plotted-by-calling-the-matplotlib-plot-function-directly."></a>
@@ -542,36 +541,35 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>years <span class="op">=</span> data.columns</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'g--'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>years <span class="op">=</span> data.columns</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a></span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'g--'</span>)</span></code></pre>
 </div>
 <figure><img src="fig/9_gdp_australia_formatted.svg" alt="GDP formatted plot for Australia" class="figure mx-auto d-block"></figure></section><section id="can-plot-many-sets-of-data-together."><h2 class="section-heading">Can plot many sets of data together.<a class="anchor" aria-label="anchor" href="#can-plot-many-sets-of-data-together."></a>
 </h2>
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Select two countries' worth of data.</span></span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
-<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a>gdp_nz <span class="op">=</span> data.loc[<span class="st">'New Zealand'</span>]</span>
-<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb8-5"><a href="#cb8-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Plot with differently-colored markers.</span></span>
-<span id="cb8-6"><a href="#cb8-6" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'b-'</span>, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
-<span id="cb8-7"><a href="#cb8-7" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_nz, <span class="st">'g-'</span>, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span>
-<span id="cb8-8"><a href="#cb8-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb8-9"><a href="#cb8-9" aria-hidden="true" tabindex="-1"></a><span class="co"># Create legend.</span></span>
-<span id="cb8-10"><a href="#cb8-10" aria-hidden="true" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'upper left'</span>)</span>
-<span id="cb8-11"><a href="#cb8-11" aria-hidden="true" tabindex="-1"></a>plt.xlabel(<span class="st">'Year'</span>)</span>
-<span id="cb8-12"><a href="#cb8-12" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita ($)'</span>)</span></code></pre>
-</div>
-<div id="adding-a-legend" class="callout callout">
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="co"># Select two countries' worth of data.</span></span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
+<span id="cb8-3"><a href="#cb8-3" tabindex="-1"></a>gdp_nz <span class="op">=</span> data.loc[<span class="st">'New Zealand'</span>]</span>
+<span id="cb8-4"><a href="#cb8-4" tabindex="-1"></a></span>
+<span id="cb8-5"><a href="#cb8-5" tabindex="-1"></a><span class="co"># Plot with differently-colored markers.</span></span>
+<span id="cb8-6"><a href="#cb8-6" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'b-'</span>, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
+<span id="cb8-7"><a href="#cb8-7" tabindex="-1"></a>plt.plot(years, gdp_nz, <span class="st">'g-'</span>, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span>
+<span id="cb8-8"><a href="#cb8-8" tabindex="-1"></a></span>
+<span id="cb8-9"><a href="#cb8-9" tabindex="-1"></a><span class="co"># Create legend.</span></span>
+<span id="cb8-10"><a href="#cb8-10" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'upper left'</span>)</span>
+<span id="cb8-11"><a href="#cb8-11" tabindex="-1"></a>plt.xlabel(<span class="st">'Year'</span>)</span>
+<span id="cb8-12"><a href="#cb8-12" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita ($)'</span>)</span></code></pre>
+</div>
+<div id="callout2" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="adding-a-legend" class="callout-inner">
-<h3 class="callout-title">Adding a Legend<a class="anchor" aria-label="anchor" href="#adding-a-legend"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="adding-a-legend">Adding a Legend<a class="anchor" aria-label="anchor" href="#adding-a-legend"></a></h3>
 <div class="callout-content">
 <p>Often when plotting multiple datasets on the same figure it is
 desirable to have a legend describing the data.</p>
@@ -580,14 +578,14 @@ <h3 class="callout-title">Adding a Legend<a class="anchor" aria-label="anchor" h
 </ul><div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_australia, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_nz, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>plt.plot(years, gdp_australia, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>plt.plot(years, gdp_nz, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span></code></pre>
 </div>
 <ul><li>Instruct <code>matplotlib</code> to create the legend.</li>
 </ul><div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a>plt.legend()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a>plt.legend()</span></code></pre>
 </div>
 <p>By default matplotlib will attempt to place the legend in a suitable
 position. If you would rather specify a position this can be done with
@@ -604,12 +602,12 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>plt.scatter(gdp_australia, gdp_nz)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>plt.scatter(gdp_australia, gdp_nz)</span></code></pre>
 </div>
 <figure><img src="fig/9_gdp_correlation_plt.svg" alt="GDP correlation using plt.scatter" class="figure mx-auto d-block"></figure><div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a>data.T.plot.scatter(x <span class="op">=</span> <span class="st">'Australia'</span>, y <span class="op">=</span> <span class="st">'New Zealand'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a>data.T.plot.scatter(x <span class="op">=</span> <span class="st">'Australia'</span>, y <span class="op">=</span> <span class="st">'New Zealand'</span>)</span></code></pre>
 </div>
 <figure><img src="fig/9_gdp_correlation_data.svg" alt="GDP correlation using data.T.plot.scatter" class="figure mx-auto d-block"></figure><div id="minima-and-maxima" class="callout challenge">
 <div class="callout-square">
@@ -625,11 +623,11 @@ <h3 class="callout-title">Minima and Maxima<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a>data_europe.____.plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
-<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a>data_europe.____</span>
-<span id="cb13-4"><a href="#cb13-4" aria-hidden="true" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
-<span id="cb13-5"><a href="#cb13-5" aria-hidden="true" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a>data_europe.____.plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
+<span id="cb13-3"><a href="#cb13-3" tabindex="-1"></a>data_europe.____</span>
+<span id="cb13-4"><a href="#cb13-4" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
+<span id="cb13-5"><a href="#cb13-5" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -639,16 +637,16 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a>data_europe.<span class="bu">min</span>().plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a>data_europe.<span class="bu">max</span>().plot(label<span class="op">=</span><span class="st">'max'</span>)</span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a>data_europe.<span class="bu">min</span>().plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a>data_europe.<span class="bu">max</span>().plot(label<span class="op">=</span><span class="st">'max'</span>)</span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
 </div>
 <figure><img src="fig/9_minima_maxima_solution.png" alt="Minima Maxima Solution" class="figure mx-auto d-block"></figure></div>
 </div>
@@ -674,13 +672,13 @@ <h3 class="callout-title">Correlations<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>data_asia.describe().T.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'min'</span>, y<span class="op">=</span><span class="st">'max'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>data_asia.describe().T.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'min'</span>, y<span class="op">=</span><span class="st">'max'</span>)</span></code></pre>
 </div>
 <figure><img src="fig/9_correlations_solution1.svg" alt="Correlations Solution 1" class="figure mx-auto d-block"></figure><p>No particular correlations can be seen between the minimum and
 maximum gdp values year on year. It seems the fortunes of asian
@@ -703,10 +701,10 @@ <h3 class="callout-title">Correlations<em>(continued)</em><a class="anchor" aria
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a>data_asia.<span class="bu">max</span>().plot()</span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmax())</span>
-<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmin())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a>data_asia.<span class="bu">max</span>().plot()</span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmax())</span>
+<span id="cb16-4"><a href="#cb16-4" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmin())</span></code></pre>
 </div>
 </div>
 </div>
@@ -716,7 +714,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <figure><img src="fig/9_correlations_solution2.png" alt="Correlations Solution 2" class="figure mx-auto d-block"></figure><p>Seems the variability in this value is due to a sharp drop after
 1972. Some geopolitics at play perhaps? Given the dominance of oil
@@ -740,9 +738,9 @@ <h3 class="callout-title">More Correlations<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>data_all <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>data_all.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'gdpPercap_2007'</span>, y<span class="op">=</span><span class="st">'lifeExp_2007'</span>,</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a>              s<span class="op">=</span>data_all[<span class="st">'pop_2007'</span>]<span class="op">/</span><span class="fl">1e6</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>data_all <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>data_all.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'gdpPercap_2007'</span>, y<span class="op">=</span><span class="st">'lifeExp_2007'</span>,</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a>              s<span class="op">=</span>data_all[<span class="st">'pop_2007'</span>]<span class="op">/</span><span class="fl">1e6</span>)</span></code></pre>
 </div>
 <p>Using online help and other resources, explain what each argument to
 <code>plot</code> does.</p>
@@ -754,7 +752,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <figure><img src="fig/9_more_correlations_solution.svg" alt="More Correlations Solution" class="figure mx-auto d-block"></figure><p>A good place to look is the documentation for the plot function -
 help(data_all.plot).</p>
@@ -769,13 +767,12 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </div>
 </div>
 </div>
-<div id="saving-your-plot-to-a-file" class="callout callout">
+<div id="callout3" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="saving-your-plot-to-a-file" class="callout-inner">
-<h3 class="callout-title">Saving your plot to a file<a class="anchor" aria-label="anchor" href="#saving-your-plot-to-a-file"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="saving-your-plot-to-a-file">Saving your plot to a file<a class="anchor" aria-label="anchor" href="#saving-your-plot-to-a-file"></a></h3>
 <div class="callout-content">
 <p>If you are satisfied with the plot you see you may want to save it to
 a file, perhaps to include it in a publication. There is a function in
@@ -784,7 +781,7 @@ <h3 class="callout-title">Saving your plot to a file<a class="anchor" aria-label
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>plt.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>plt.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
 </div>
 <p>will save the current figure to the file <code>my_figure.png</code>.
 The file format will automatically be deduced from the file name
@@ -803,20 +800,19 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a>data.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>fig <span class="op">=</span> plt.gcf() <span class="co"># get current figure</span></span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a>fig.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a>data.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>fig <span class="op">=</span> plt.gcf() <span class="co"># get current figure</span></span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a>fig.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
 </div>
 </div>
 </div>
 </div>
-<div id="making-your-plots-accessible" class="callout callout">
+<div id="callout4" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="making-your-plots-accessible" class="callout-inner">
-<h3 class="callout-title">Making your plots accessible<a class="anchor" aria-label="anchor" href="#making-your-plots-accessible"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="making-your-plots-accessible">Making your plots accessible<a class="anchor" aria-label="anchor" href="#making-your-plots-accessible"></a></h3>
 <div class="callout-content">
 <p>Whenever you are generating plots to go into a paper or a
 presentation, there are a few things you can do to make sure that
@@ -918,7 +914,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/09-plotting.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-06-08",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/10-lunch.html b/10-lunch.html
index 978dbb975..1d281393b 100644
--- a/10-lunch.html
+++ b/10-lunch.html
@@ -456,7 +456,7 @@ <h1>Lunch</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/10-lunch.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/11-lists.html b/11-lists.html
index a6fc343a6..b6c661e82 100644
--- a/11-lists.html
+++ b/11-lists.html
@@ -442,9 +442,9 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>pressures <span class="op">=</span> [<span class="fl">0.273</span>, <span class="fl">0.275</span>, <span class="fl">0.277</span>, <span class="fl">0.275</span>, <span class="fl">0.276</span>]</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures:'</span>, pressures)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'length:'</span>, <span class="bu">len</span>(pressures))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>pressures <span class="op">=</span> [<span class="fl">0.273</span>, <span class="fl">0.275</span>, <span class="fl">0.277</span>, <span class="fl">0.275</span>, <span class="fl">0.276</span>]</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures:'</span>, pressures)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'length:'</span>, <span class="bu">len</span>(pressures))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -458,8 +458,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth item of pressures:'</span>, pressures[<span class="dv">0</span>])</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'fourth item of pressures:'</span>, pressures[<span class="dv">4</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth item of pressures:'</span>, pressures[<span class="dv">0</span>])</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'fourth item of pressures:'</span>, pressures[<span class="dv">4</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -474,8 +474,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>pressures[<span class="dv">0</span>] <span class="op">=</span> <span class="fl">0.265</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures is now:'</span>, pressures)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>pressures[<span class="dv">0</span>] <span class="op">=</span> <span class="fl">0.265</span></span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures is now:'</span>, pressures)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -489,10 +489,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is initially:'</span>, primes)</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>primes.append(<span class="dv">7</span>)</span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has become:'</span>, primes)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is initially:'</span>, primes)</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a>primes.append(<span class="dv">7</span>)</span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has become:'</span>, primes)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -516,13 +516,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>teen_primes <span class="op">=</span> [<span class="dv">11</span>, <span class="dv">13</span>, <span class="dv">17</span>, <span class="dv">19</span>]</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>middle_aged_primes <span class="op">=</span> [<span class="dv">37</span>, <span class="dv">41</span>, <span class="dv">43</span>, <span class="dv">47</span>]</span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is currently:'</span>, primes)</span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a>primes.extend(teen_primes)</span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has now become:'</span>, primes)</span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a>primes.append(middle_aged_primes)</span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has finally become:'</span>, primes)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>teen_primes <span class="op">=</span> [<span class="dv">11</span>, <span class="dv">13</span>, <span class="dv">17</span>, <span class="dv">19</span>]</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>middle_aged_primes <span class="op">=</span> [<span class="dv">37</span>, <span class="dv">41</span>, <span class="dv">43</span>, <span class="dv">47</span>]</span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is currently:'</span>, primes)</span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a>primes.extend(teen_primes)</span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has now become:'</span>, primes)</span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a>primes.append(middle_aged_primes)</span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has finally become:'</span>, primes)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -545,10 +545,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>, <span class="dv">7</span>, <span class="dv">9</span>]</span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes before removing last item:'</span>, primes)</span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a><span class="kw">del</span> primes[<span class="dv">4</span>]</span>
-<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes after removing last item:'</span>, primes)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>, <span class="dv">7</span>, <span class="dv">9</span>]</span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes before removing last item:'</span>, primes)</span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a><span class="kw">del</span> primes[<span class="dv">4</span>]</span>
+<span id="cb11-4"><a href="#cb11-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes after removing last item:'</span>, primes)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -570,7 +570,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>goals <span class="op">=</span> [<span class="dv">1</span>, <span class="st">'Create lists.'</span>, <span class="dv">2</span>, <span class="st">'Extract items from lists.'</span>, <span class="dv">3</span>, <span class="st">'Modify lists.'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>goals <span class="op">=</span> [<span class="dv">1</span>, <span class="st">'Create lists.'</span>, <span class="dv">2</span>, <span class="st">'Extract items from lists.'</span>, <span class="dv">3</span>, <span class="st">'Modify lists.'</span>]</span></code></pre>
 </div>
 </section><section id="character-strings-can-be-indexed-like-lists."><h2 class="section-heading">Character strings can be indexed like lists.<a class="anchor" aria-label="anchor" href="#character-strings-can-be-indexed-like-lists."></a>
 </h2>
@@ -579,9 +579,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'carbon'</span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth character:'</span>, element[<span class="dv">0</span>])</span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'third character:'</span>, element[<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'carbon'</span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth character:'</span>, element[<span class="dv">0</span>])</span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'third character:'</span>, element[<span class="dv">3</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -602,7 +602,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>element[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'C'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>element[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'C'</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -621,7 +621,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'99th element of element is:'</span>, element[<span class="dv">99</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'99th element of element is:'</span>, element[<span class="dv">99</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -641,13 +641,13 @@ <h3 class="callout-title">Fill in the Blanks<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> ____</span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>values.____(<span class="dv">1</span>)</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a>values.____(<span class="dv">3</span>)</span>
-<span id="cb20-4"><a href="#cb20-4" aria-hidden="true" tabindex="-1"></a>values.____(<span class="dv">5</span>)</span>
-<span id="cb20-5"><a href="#cb20-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
-<span id="cb20-6"><a href="#cb20-6" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> values[____]</span>
-<span id="cb20-7"><a href="#cb20-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>values <span class="op">=</span> ____</span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>values.____(<span class="dv">1</span>)</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a>values.____(<span class="dv">3</span>)</span>
+<span id="cb20-4"><a href="#cb20-4" tabindex="-1"></a>values.____(<span class="dv">5</span>)</span>
+<span id="cb20-5"><a href="#cb20-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
+<span id="cb20-6"><a href="#cb20-6" tabindex="-1"></a>values <span class="op">=</span> values[____]</span>
+<span id="cb20-7"><a href="#cb20-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -668,13 +668,13 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> []</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>values.append(<span class="dv">1</span>)</span>
-<span id="cb22-3"><a href="#cb22-3" aria-hidden="true" tabindex="-1"></a>values.append(<span class="dv">3</span>)</span>
-<span id="cb22-4"><a href="#cb22-4" aria-hidden="true" tabindex="-1"></a>values.append(<span class="dv">5</span>)</span>
-<span id="cb22-5"><a href="#cb22-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
-<span id="cb22-6"><a href="#cb22-6" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> values[<span class="dv">1</span>:]</span>
-<span id="cb22-7"><a href="#cb22-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>values <span class="op">=</span> []</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>values.append(<span class="dv">1</span>)</span>
+<span id="cb22-3"><a href="#cb22-3" tabindex="-1"></a>values.append(<span class="dv">3</span>)</span>
+<span id="cb22-4"><a href="#cb22-4" tabindex="-1"></a>values.append(<span class="dv">5</span>)</span>
+<span id="cb22-5"><a href="#cb22-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
+<span id="cb22-6"><a href="#cb22-6" tabindex="-1"></a>values <span class="op">=</span> values[<span class="dv">1</span>:]</span>
+<span id="cb22-7"><a href="#cb22-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
 </div>
 </div>
 </div>
@@ -723,8 +723,8 @@ <h3 class="callout-title">From Strings to Lists and Back<a class="anchor" aria-l
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'string to list:'</span>, <span class="bu">list</span>(<span class="st">'tin'</span>))</span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'list to string:'</span>, <span class="st">''</span>.join([<span class="st">'g'</span>, <span class="st">'o'</span>, <span class="st">'l'</span>, <span class="st">'d'</span>]))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'string to list:'</span>, <span class="bu">list</span>(<span class="st">'tin'</span>))</span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'list to string:'</span>, <span class="st">''</span>.join([<span class="st">'g'</span>, <span class="st">'o'</span>, <span class="st">'l'</span>, <span class="st">'d'</span>]))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -769,8 +769,8 @@ <h3 class="callout-title">Working With the End<a class="anchor" aria-label="anch
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'helium'</span></span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'helium'</span></span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>How does Python interpret a negative index?</li>
 <li>If a list or string has N elements, what is the most negative index
@@ -817,9 +817,9 @@ <h3 class="callout-title">Stepping Through a List<a class="anchor" aria-label="a
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'fluorine'</span></span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="dv">2</span>])</span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'fluorine'</span></span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="dv">2</span>])</span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>If we write a slice as <code>low:high:stride</code>, what does
 <code>stride</code> do?</li>
@@ -839,8 +839,8 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>furn</span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>eniroulf</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>furn</span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>eniroulf</span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>
 <code>stride</code> is the step size of the slice.</li>
@@ -865,9 +865,9 @@ <h3 class="callout-title">Slice Bounds<a class="anchor" aria-label="anchor" href
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'lithium'</span></span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[<span class="dv">0</span>:<span class="dv">20</span>])</span>
-<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'lithium'</span></span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a><span class="bu">print</span>(element[<span class="dv">0</span>:<span class="dv">20</span>])</span>
+<span id="cb28-3"><a href="#cb28-3" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -905,18 +905,18 @@ <h3 class="callout-title">Sort and Sorted<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program A</span></span>
-<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb30-3"><a href="#cb30-3" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">sorted</span>(letters)</span>
-<span id="cb30-4"><a href="#cb30-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a><span class="co"># Program A</span></span>
+<span id="cb30-2"><a href="#cb30-2" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb30-3"><a href="#cb30-3" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">sorted</span>(letters)</span>
+<span id="cb30-4"><a href="#cb30-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program B</span></span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> letters.sort()</span>
-<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a><span class="co"># Program B</span></span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb31-3"><a href="#cb31-3" tabindex="-1"></a>result <span class="op">=</span> letters.sort()</span>
+<span id="cb31-4"><a href="#cb31-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -962,20 +962,20 @@ <h3 class="callout-title">Copying (or Not)<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program A</span></span>
-<span id="cb34-2"><a href="#cb34-2" aria-hidden="true" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb34-3"><a href="#cb34-3" aria-hidden="true" tabindex="-1"></a>new <span class="op">=</span> old      <span class="co"># simple assignment</span></span>
-<span id="cb34-4"><a href="#cb34-4" aria-hidden="true" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
-<span id="cb34-5"><a href="#cb34-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a><span class="co"># Program A</span></span>
+<span id="cb34-2"><a href="#cb34-2" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb34-3"><a href="#cb34-3" tabindex="-1"></a>new <span class="op">=</span> old      <span class="co"># simple assignment</span></span>
+<span id="cb34-4"><a href="#cb34-4" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
+<span id="cb34-5"><a href="#cb34-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program B</span></span>
-<span id="cb35-2"><a href="#cb35-2" aria-hidden="true" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb35-3"><a href="#cb35-3" aria-hidden="true" tabindex="-1"></a>new <span class="op">=</span> old[:]   <span class="co"># assigning a slice</span></span>
-<span id="cb35-4"><a href="#cb35-4" aria-hidden="true" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
-<span id="cb35-5"><a href="#cb35-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a><span class="co"># Program B</span></span>
+<span id="cb35-2"><a href="#cb35-2" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb35-3"><a href="#cb35-3" tabindex="-1"></a>new <span class="op">=</span> old[:]   <span class="co"># assigning a slice</span></span>
+<span id="cb35-4"><a href="#cb35-4" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
+<span id="cb35-5"><a href="#cb35-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
 </div>
 </div>
 </div>
@@ -1089,7 +1089,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/11-lists.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-07-24",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/12-for-loops.html b/12-for-loops.html
index 686811719..27fdd6e8f 100644
--- a/12-for-loops.html
+++ b/12-for-loops.html
@@ -443,16 +443,16 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 <ul><li>This <code>for</code> loop is equivalent to:</li>
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">2</span>)</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">3</span>)</span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">2</span>)</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">3</span>)</span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span>)</span></code></pre>
 </div>
 <ul><li>And the <code>for</code> loop’s output is:</li>
 </ul><div class="codewrapper">
@@ -468,8 +468,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 <ul><li>The collection, <code>[2, 3, 5]</code>, is what the loop is being
 run on.</li>
@@ -492,8 +492,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="bu">print</span>(number)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -504,8 +504,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>firstName <span class="op">=</span> <span class="st">"Jon"</span></span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>  lastName <span class="op">=</span> <span class="st">"Smith"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>firstName <span class="op">=</span> <span class="st">"Jon"</span></span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>  lastName <span class="op">=</span> <span class="st">"Smith"</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -526,8 +526,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> kitten <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(kitten)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="cf">for</span> kitten <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>    <span class="bu">print</span>(kitten)</span></code></pre>
 </div>
 </section><section id="the-body-of-a-loop-can-contain-many-statements."><h2 class="section-heading">The body of a loop can contain many statements.<a class="anchor" aria-label="anchor" href="#the-body-of-a-loop-can-contain-many-statements."></a>
 </h2>
@@ -536,11 +536,11 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> p <span class="kw">in</span> primes:</span>
-<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>    squared <span class="op">=</span> p <span class="op">**</span> <span class="dv">2</span></span>
-<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a>    cubed <span class="op">=</span> p <span class="op">**</span> <span class="dv">3</span></span>
-<span id="cb10-5"><a href="#cb10-5" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(p, squared, cubed)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a><span class="cf">for</span> p <span class="kw">in</span> primes:</span>
+<span id="cb10-3"><a href="#cb10-3" tabindex="-1"></a>    squared <span class="op">=</span> p <span class="op">**</span> <span class="dv">2</span></span>
+<span id="cb10-4"><a href="#cb10-4" tabindex="-1"></a>    cubed <span class="op">=</span> p <span class="op">**</span> <span class="dv">3</span></span>
+<span id="cb10-5"><a href="#cb10-5" tabindex="-1"></a>    <span class="bu">print</span>(p, squared, cubed)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -565,9 +565,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'a range is not a list: range(0, 3)'</span>)</span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>, <span class="dv">3</span>):</span>
-<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'a range is not a list: range(0, 3)'</span>)</span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>, <span class="dv">3</span>):</span>
+<span id="cb12-3"><a href="#cb12-3" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -587,11 +587,11 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Sum the first 10 integers.</span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a>   total <span class="op">=</span> total <span class="op">+</span> (number <span class="op">+</span> <span class="dv">1</span>)</span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a><span class="co"># Sum the first 10 integers.</span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a>   total <span class="op">=</span> total <span class="op">+</span> (number <span class="op">+</span> <span class="dv">1</span>)</span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -624,7 +624,7 @@ <h3 class="callout-title">Classifying Errors<a class="anchor" aria-label="anchor
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>An IndentationError is a syntax error. Programs with syntax errors
 cannot be started. A program with a runtime error will start but an
@@ -647,9 +647,9 @@ <h3 class="callout-title">Tracing Execution<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> <span class="st">"tin"</span>:</span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> <span class="st">"tin"</span>:</span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="dv">1</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -659,7 +659,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <table class="table"><thead><tr class="header"><th>Line no</th>
 <th>Variables</th>
@@ -694,11 +694,11 @@ <h3 class="callout-title">Reversing a String<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> ____</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
-<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> ____</span>
-<span id="cb17-5"><a href="#cb17-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>result <span class="op">=</span> ____</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
+<span id="cb17-4"><a href="#cb17-4" tabindex="-1"></a>    result <span class="op">=</span> ____</span>
+<span id="cb17-5"><a href="#cb17-5" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -708,16 +708,16 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
-<span id="cb18-2"><a href="#cb18-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb18-3"><a href="#cb18-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
-<span id="cb18-4"><a href="#cb18-4" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> char <span class="op">+</span> result</span>
-<span id="cb18-5"><a href="#cb18-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
+<span id="cb18-2"><a href="#cb18-2" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb18-3"><a href="#cb18-3" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
+<span id="cb18-4"><a href="#cb18-4" tabindex="-1"></a>    result <span class="op">=</span> char <span class="op">+</span> result</span>
+<span id="cb18-5"><a href="#cb18-5" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -736,11 +736,11 @@ <h3 class="callout-title">Practice Accumulating<a class="anchor" aria-label="anc
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Total length of the strings in the list: ["red", "green", "blue"] =&gt; 12</span></span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb19-4"><a href="#cb19-4" aria-hidden="true" tabindex="-1"></a>    ____ <span class="op">=</span> ____ <span class="op">+</span> <span class="bu">len</span>(word)</span>
-<span id="cb19-5"><a href="#cb19-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="co"># Total length of the strings in the list: ["red", "green", "blue"] =&gt; 12</span></span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb19-4"><a href="#cb19-4" tabindex="-1"></a>    ____ <span class="op">=</span> ____ <span class="op">+</span> <span class="bu">len</span>(word)</span>
+<span id="cb19-5"><a href="#cb19-5" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
 </div>
 </div>
 </div>
@@ -750,15 +750,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="bu">len</span>(word)</span>
-<span id="cb20-4"><a href="#cb20-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="bu">len</span>(word)</span>
+<span id="cb20-4"><a href="#cb20-4" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
 </div>
 </div>
 </div>
@@ -775,11 +775,11 @@ <h3 class="callout-title">Practice Accumulating<em>(continued)</em><a class="anc
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="co"># List of word lengths: ["red", "green", "blue"] =&gt; [3, 5, 4]</span></span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a>lengths <span class="op">=</span> ____</span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb21-4"><a href="#cb21-4" aria-hidden="true" tabindex="-1"></a>    lengths.____(____)</span>
-<span id="cb21-5"><a href="#cb21-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a><span class="co"># List of word lengths: ["red", "green", "blue"] =&gt; [3, 5, 4]</span></span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a>lengths <span class="op">=</span> ____</span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb21-4"><a href="#cb21-4" tabindex="-1"></a>    lengths.____(____)</span>
+<span id="cb21-5"><a href="#cb21-5" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
 </div>
 </div>
 </div>
@@ -789,15 +789,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>lengths <span class="op">=</span> []</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb22-3"><a href="#cb22-3" aria-hidden="true" tabindex="-1"></a>    lengths.append(<span class="bu">len</span>(word))</span>
-<span id="cb22-4"><a href="#cb22-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>lengths <span class="op">=</span> []</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb22-3"><a href="#cb22-3" tabindex="-1"></a>    lengths.append(<span class="bu">len</span>(word))</span>
+<span id="cb22-4"><a href="#cb22-4" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
 </div>
 </div>
 </div>
@@ -814,12 +814,12 @@ <h3 class="callout-title">Practice Accumulating<em>(continued)</em><a class="anc
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Concatenate all words: ["red", "green", "blue"] =&gt; "redgreenblue"</span></span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
-<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> ____</span>
-<span id="cb23-4"><a href="#cb23-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> ____ <span class="kw">in</span> ____:</span>
-<span id="cb23-5"><a href="#cb23-5" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb23-6"><a href="#cb23-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="co"># Concatenate all words: ["red", "green", "blue"] =&gt; "redgreenblue"</span></span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
+<span id="cb23-3"><a href="#cb23-3" tabindex="-1"></a>result <span class="op">=</span> ____</span>
+<span id="cb23-4"><a href="#cb23-4" tabindex="-1"></a><span class="cf">for</span> ____ <span class="kw">in</span> ____:</span>
+<span id="cb23-5"><a href="#cb23-5" tabindex="-1"></a>    ____</span>
+<span id="cb23-6"><a href="#cb23-6" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -829,16 +829,16 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Show me the solution</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> words:</span>
-<span id="cb24-4"><a href="#cb24-4" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> result <span class="op">+</span> word</span>
-<span id="cb24-5"><a href="#cb24-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb24-3"><a href="#cb24-3" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> words:</span>
+<span id="cb24-4"><a href="#cb24-4" tabindex="-1"></a>    result <span class="op">=</span> result <span class="op">+</span> word</span>
+<span id="cb24-5"><a href="#cb24-5" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -865,15 +865,15 @@ <h3 class="callout-title">Practice Accumulating<em>(continued)</em><a class="anc
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a>acronym <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a>    acronym <span class="op">=</span> acronym <span class="op">+</span> word[<span class="dv">0</span>].upper()</span>
-<span id="cb25-4"><a href="#cb25-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(acronym)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a>acronym <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a>    acronym <span class="op">=</span> acronym <span class="op">+</span> word[<span class="dv">0</span>].upper()</span>
+<span id="cb25-4"><a href="#cb25-4" tabindex="-1"></a><span class="bu">print</span>(acronym)</span></code></pre>
 </div>
 </div>
 </div>
@@ -893,13 +893,13 @@ <h3 class="callout-title">Cumulative Sum<a class="anchor" aria-label="anchor" hr
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>cumulative.append(total)</span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
-<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> total <span class="op">+</span> number</span>
-<span id="cb26-5"><a href="#cb26-5" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb26-6"><a href="#cb26-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span>
-<span id="cb26-7"><a href="#cb26-7" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>cumulative.append(total)</span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
+<span id="cb26-4"><a href="#cb26-4" tabindex="-1"></a>total <span class="op">=</span> total <span class="op">+</span> number</span>
+<span id="cb26-5"><a href="#cb26-5" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb26-6"><a href="#cb26-6" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span>
+<span id="cb26-7"><a href="#cb26-7" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -909,18 +909,18 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Show me the solution</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span>
-<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
-<span id="cb27-4"><a href="#cb27-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
-<span id="cb27-5"><a href="#cb27-5" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> number</span>
-<span id="cb27-6"><a href="#cb27-6" aria-hidden="true" tabindex="-1"></a>    cumulative.append(total)</span>
-<span id="cb27-7"><a href="#cb27-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span>
+<span id="cb27-3"><a href="#cb27-3" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
+<span id="cb27-4"><a href="#cb27-4" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
+<span id="cb27-5"><a href="#cb27-5" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> number</span>
+<span id="cb27-6"><a href="#cb27-6" tabindex="-1"></a>    cumulative.append(total)</span>
+<span id="cb27-7"><a href="#cb27-7" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span></code></pre>
 </div>
 </div>
 </div>
@@ -945,13 +945,13 @@ <h3 class="callout-title">Identifying Variable Name Errors<a class="anchor" aria
 </ol><div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
-<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> (Number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb28-4"><a href="#cb28-4" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> a</span>
-<span id="cb28-5"><a href="#cb28-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb28-6"><a href="#cb28-6" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
-<span id="cb28-7"><a href="#cb28-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
+<span id="cb28-3"><a href="#cb28-3" tabindex="-1"></a>    <span class="cf">if</span> (Number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb28-4"><a href="#cb28-4" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> a</span>
+<span id="cb28-5"><a href="#cb28-5" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb28-6"><a href="#cb28-6" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
+<span id="cb28-7"><a href="#cb28-7" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
 </div>
 </div>
 </div>
@@ -961,7 +961,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution9" aria-expanded="false" aria-controls="collapseSolution9">
   <h4 class="accordion-header" id="headingSolution9">Show me the solution</h4>
 </button>
-<div id="collapseSolution9" class="accordion-collapse collapse" data-bs-parent="#accordionSolution9" aria-labelledby="headingSolution9">
+<div id="collapseSolution9" class="accordion-collapse collapse" aria-labelledby="headingSolution9" data-bs-parent="#accordionSolution9">
 <div class="accordion-body">
 <ul><li>Python variable names are case sensitive: <code>number</code> and
 <code>Number</code> refer to different variables.</li>
@@ -972,14 +972,14 @@ <h4 class="accordion-header" id="headingSolution9">Show me the solution</h4>
 </ul><div class="codewrapper sourceCode" id="cb29">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a>message <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
-<span id="cb29-4"><a href="#cb29-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> (number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb29-5"><a href="#cb29-5" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"a"</span></span>
-<span id="cb29-6"><a href="#cb29-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb29-7"><a href="#cb29-7" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
-<span id="cb29-8"><a href="#cb29-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" tabindex="-1"></a>message <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb29-2"><a href="#cb29-2" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb29-3"><a href="#cb29-3" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
+<span id="cb29-4"><a href="#cb29-4" tabindex="-1"></a>    <span class="cf">if</span> (number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb29-5"><a href="#cb29-5" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"a"</span></span>
+<span id="cb29-6"><a href="#cb29-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb29-7"><a href="#cb29-7" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
+<span id="cb29-8"><a href="#cb29-8" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
 </div>
 </div>
 </div>
@@ -1001,8 +1001,8 @@ <h3 class="callout-title">Identifying Item Errors<a class="anchor" aria-label="a
 </ol><div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
-<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">4</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
+<span id="cb30-2"><a href="#cb30-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">4</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -1012,15 +1012,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution10" aria-expanded="false" aria-controls="collapseSolution10">
   <h4 class="accordion-header" id="headingSolution10">Show me the solution</h4>
 </button>
-<div id="collapseSolution10" class="accordion-collapse collapse" data-bs-parent="#accordionSolution10" aria-labelledby="headingSolution10">
+<div id="collapseSolution10" class="accordion-collapse collapse" aria-labelledby="headingSolution10" data-bs-parent="#accordionSolution10">
 <div class="accordion-body">
 <p>This list has 4 elements and the index to access the last element in
 the list is <code>3</code>.</p>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">3</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -1108,7 +1108,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/12-for-loops.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/13-conditionals.html b/13-conditionals.html
index b3a5251fd..3508c379d 100644
--- a/13-conditionals.html
+++ b/13-conditionals.html
@@ -443,13 +443,13 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">3.54</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(mass, <span class="st">'is large'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">2.07</span></span>
-<span id="cb1-6"><a href="#cb1-6" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb1-7"><a href="#cb1-7" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span> (mass, <span class="st">'is large'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">3.54</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    <span class="bu">print</span>(mass, <span class="st">'is large'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a></span>
+<span id="cb1-5"><a href="#cb1-5" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">2.07</span></span>
+<span id="cb1-6"><a href="#cb1-6" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb1-7"><a href="#cb1-7" tabindex="-1"></a>    <span class="bu">print</span> (mass, <span class="st">'is large'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -464,10 +464,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
-<span id="cb3-3"><a href="#cb3-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb3-4"><a href="#cb3-4" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
+<span id="cb3-3"><a href="#cb3-3" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb3-4"><a href="#cb3-4" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -485,12 +485,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb5-6"><a href="#cb5-6" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -513,14 +513,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">9.0</span>:</span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is HUGE'</span>)</span>
-<span id="cb7-5"><a href="#cb7-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb7-6"><a href="#cb7-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
-<span id="cb7-7"><a href="#cb7-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb7-8"><a href="#cb7-8" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">9.0</span>:</span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is HUGE'</span>)</span>
+<span id="cb7-5"><a href="#cb7-5" tabindex="-1"></a>    <span class="cf">elif</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb7-6"><a href="#cb7-6" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
+<span id="cb7-7"><a href="#cb7-7" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb7-8"><a href="#cb7-8" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -539,13 +539,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>grade <span class="op">=</span> <span class="dv">85</span></span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> grade <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is A'</span>)</span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">80</span>:</span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is B'</span>)</span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is C'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>grade <span class="op">=</span> <span class="dv">85</span></span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="cf">if</span> grade <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is A'</span>)</span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">80</span>:</span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is B'</span>)</span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is C'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -557,12 +557,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
-<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a><span class="cf">else</span>:</span>
-<span id="cb11-5"><a href="#cb11-5" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'adjusting velocity'</span>)</span>
-<span id="cb11-6"><a href="#cb11-6" aria-hidden="true" tabindex="-1"></a>    velocity <span class="op">=</span> <span class="fl">50.0</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
+<span id="cb11-4"><a href="#cb11-4" tabindex="-1"></a><span class="cf">else</span>:</span>
+<span id="cb11-5"><a href="#cb11-5" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'adjusting velocity'</span>)</span>
+<span id="cb11-6"><a href="#cb11-6" tabindex="-1"></a>    velocity <span class="op">=</span> <span class="fl">50.0</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -574,16 +574,16 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>): <span class="co"># execute the loop 5 times</span></span>
-<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(i, <span class="st">':'</span>, velocity)</span>
-<span id="cb13-4"><a href="#cb13-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
-<span id="cb13-5"><a href="#cb13-5" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
-<span id="cb13-6"><a href="#cb13-6" aria-hidden="true" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">-</span> <span class="fl">5.0</span></span>
-<span id="cb13-7"><a href="#cb13-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb13-8"><a href="#cb13-8" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too slow'</span>)</span>
-<span id="cb13-9"><a href="#cb13-9" aria-hidden="true" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">+</span> <span class="fl">10.0</span></span>
-<span id="cb13-10"><a href="#cb13-10" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'final velocity:'</span>, velocity)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>): <span class="co"># execute the loop 5 times</span></span>
+<span id="cb13-3"><a href="#cb13-3" tabindex="-1"></a>    <span class="bu">print</span>(i, <span class="st">':'</span>, velocity)</span>
+<span id="cb13-4"><a href="#cb13-4" tabindex="-1"></a>    <span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
+<span id="cb13-5"><a href="#cb13-5" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
+<span id="cb13-6"><a href="#cb13-6" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">-</span> <span class="fl">5.0</span></span>
+<span id="cb13-7"><a href="#cb13-7" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb13-8"><a href="#cb13-8" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too slow'</span>)</span>
+<span id="cb13-9"><a href="#cb13-9" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">+</span> <span class="fl">10.0</span></span>
+<span id="cb13-10"><a href="#cb13-10" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'final velocity:'</span>, velocity)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -673,13 +673,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <em>outside</em> the body of the loop to show the final value of
 <code>velocity</code>, since its value is updated by the last iteration
 of the loop.</li>
-</ul><div id="compound-relations-using-and-or-and-parentheses" class="callout callout">
+</ul><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="compound-relations-using-and-or-and-parentheses" class="callout-inner">
-<h3 class="callout-title">Compound Relations Using<code>and</code>,<code>or</code>, and Parentheses<a class="anchor" aria-label="anchor" href="#compound-relations-using-and-or-and-parentheses"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="compound-relations-using-and-or-and-parentheses">Compound Relations Using <code>and</code>,
+<code>or</code>, and Parentheses<a class="anchor" aria-label="anchor" href="#compound-relations-using-and-or-and-parentheses"></a></h3>
 <div class="callout-content">
 <p>Often, you want some combination of things to be true. You can
 combine relations within a conditional using <code>and</code> and
@@ -687,19 +687,19 @@ <h3 class="callout-title">Compound Relations Using<code>and</code>,<code>or</cod
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>mass     <span class="op">=</span> [ <span class="fl">3.54</span>,  <span class="fl">2.07</span>,  <span class="fl">9.22</span>,  <span class="fl">1.86</span>,  <span class="fl">1.71</span>]</span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>velocity <span class="op">=</span> [<span class="fl">10.00</span>, <span class="fl">20.00</span>, <span class="fl">30.00</span>, <span class="fl">25.00</span>, <span class="fl">20.00</span>]</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>):</span>
-<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> mass[i] <span class="op">&gt;</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
-<span id="cb15-7"><a href="#cb15-7" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Fast heavy object.  Duck!"</span>)</span>
-<span id="cb15-8"><a href="#cb15-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&gt;</span> <span class="dv">2</span> <span class="kw">and</span> mass[i] <span class="op">&lt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
-<span id="cb15-9"><a href="#cb15-9" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Normal traffic"</span>)</span>
-<span id="cb15-10"><a href="#cb15-10" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
-<span id="cb15-11"><a href="#cb15-11" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Slow light object.  Ignore it"</span>)</span>
-<span id="cb15-12"><a href="#cb15-12" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb15-13"><a href="#cb15-13" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Whoa!  Something is up with the data.  Check it"</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a>mass     <span class="op">=</span> [ <span class="fl">3.54</span>,  <span class="fl">2.07</span>,  <span class="fl">9.22</span>,  <span class="fl">1.86</span>,  <span class="fl">1.71</span>]</span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>velocity <span class="op">=</span> [<span class="fl">10.00</span>, <span class="fl">20.00</span>, <span class="fl">30.00</span>, <span class="fl">25.00</span>, <span class="fl">20.00</span>]</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a></span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb15-5"><a href="#cb15-5" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>):</span>
+<span id="cb15-6"><a href="#cb15-6" tabindex="-1"></a>    <span class="cf">if</span> mass[i] <span class="op">&gt;</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
+<span id="cb15-7"><a href="#cb15-7" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Fast heavy object.  Duck!"</span>)</span>
+<span id="cb15-8"><a href="#cb15-8" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&gt;</span> <span class="dv">2</span> <span class="kw">and</span> mass[i] <span class="op">&lt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
+<span id="cb15-9"><a href="#cb15-9" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Normal traffic"</span>)</span>
+<span id="cb15-10"><a href="#cb15-10" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
+<span id="cb15-11"><a href="#cb15-11" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Slow light object.  Ignore it"</span>)</span>
+<span id="cb15-12"><a href="#cb15-12" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb15-13"><a href="#cb15-13" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Whoa!  Something is up with the data.  Check it"</span>)</span></code></pre>
 </div>
 <p>Just like with arithmetic, you can and should use parentheses
 whenever there is possible ambiguity. A good general rule is to
@@ -708,14 +708,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span></code></pre>
 </div>
 <p>write one of these:</p>
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> (mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span>) <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> (mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>):</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="cf">if</span> (mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span>) <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> (mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>):</span></code></pre>
 </div>
 <p>so it is perfectly clear to a reader (and to Python) what you really
 mean.</p>
@@ -734,12 +734,12 @@ <h3 class="callout-title">Tracing Execution<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">71.9</span></span>
-<span id="cb18-2"><a href="#cb18-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> pressure <span class="op">&gt;</span> <span class="fl">50.0</span>:</span>
-<span id="cb18-3"><a href="#cb18-3" aria-hidden="true" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">25.0</span></span>
-<span id="cb18-4"><a href="#cb18-4" aria-hidden="true" tabindex="-1"></a><span class="cf">elif</span> pressure <span class="op">&lt;=</span> <span class="fl">50.0</span>:</span>
-<span id="cb18-5"><a href="#cb18-5" aria-hidden="true" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">0.0</span></span>
-<span id="cb18-6"><a href="#cb18-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(pressure)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">71.9</span></span>
+<span id="cb18-2"><a href="#cb18-2" tabindex="-1"></a><span class="cf">if</span> pressure <span class="op">&gt;</span> <span class="fl">50.0</span>:</span>
+<span id="cb18-3"><a href="#cb18-3" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">25.0</span></span>
+<span id="cb18-4"><a href="#cb18-4" tabindex="-1"></a><span class="cf">elif</span> pressure <span class="op">&lt;=</span> <span class="fl">50.0</span>:</span>
+<span id="cb18-5"><a href="#cb18-5" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">0.0</span></span>
+<span id="cb18-6"><a href="#cb18-6" tabindex="-1"></a><span class="bu">print</span>(pressure)</span></code></pre>
 </div>
 </div>
 </div>
@@ -774,14 +774,14 @@ <h3 class="callout-title">Trimming Values<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> ____</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
-<span id="cb20-4"><a href="#cb20-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
-<span id="cb20-5"><a href="#cb20-5" aria-hidden="true" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
-<span id="cb20-6"><a href="#cb20-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb20-7"><a href="#cb20-7" aria-hidden="true" tabindex="-1"></a>        ____</span>
-<span id="cb20-8"><a href="#cb20-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>result <span class="op">=</span> ____</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
+<span id="cb20-4"><a href="#cb20-4" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
+<span id="cb20-5"><a href="#cb20-5" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
+<span id="cb20-6"><a href="#cb20-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb20-7"><a href="#cb20-7" tabindex="-1"></a>        ____</span>
+<span id="cb20-8"><a href="#cb20-8" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -801,14 +801,14 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> []</span>
-<span id="cb22-3"><a href="#cb22-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
-<span id="cb22-4"><a href="#cb22-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> value <span class="op">&lt;</span> <span class="fl">0.0</span>:</span>
-<span id="cb22-5"><a href="#cb22-5" aria-hidden="true" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
-<span id="cb22-6"><a href="#cb22-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb22-7"><a href="#cb22-7" aria-hidden="true" tabindex="-1"></a>        result.append(<span class="dv">1</span>)</span>
-<span id="cb22-8"><a href="#cb22-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>result <span class="op">=</span> []</span>
+<span id="cb22-3"><a href="#cb22-3" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
+<span id="cb22-4"><a href="#cb22-4" tabindex="-1"></a>    <span class="cf">if</span> value <span class="op">&lt;</span> <span class="fl">0.0</span>:</span>
+<span id="cb22-5"><a href="#cb22-5" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
+<span id="cb22-6"><a href="#cb22-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb22-7"><a href="#cb22-7" tabindex="-1"></a>        result.append(<span class="dv">1</span>)</span>
+<span id="cb22-8"><a href="#cb22-8" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -827,12 +827,12 @@ <h3 class="callout-title">Processing Small Files<a class="anchor" aria-label="an
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb23-4"><a href="#cb23-4" aria-hidden="true" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb23-5"><a href="#cb23-5" aria-hidden="true" tabindex="-1"></a>    ____:</span>
-<span id="cb23-6"><a href="#cb23-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb23-3"><a href="#cb23-3" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb23-4"><a href="#cb23-4" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb23-5"><a href="#cb23-5" tabindex="-1"></a>    ____:</span>
+<span id="cb23-6"><a href="#cb23-6" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
 </div>
 </div>
 </div>
@@ -847,12 +847,12 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb24-4"><a href="#cb24-4" aria-hidden="true" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb24-5"><a href="#cb24-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(contents) <span class="op">&lt;</span> <span class="dv">50</span>:</span>
-<span id="cb24-6"><a href="#cb24-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb24-3"><a href="#cb24-3" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb24-4"><a href="#cb24-4" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb24-5"><a href="#cb24-5" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(contents) <span class="op">&lt;</span> <span class="dv">50</span>:</span>
+<span id="cb24-6"><a href="#cb24-6" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
 </div>
 </div>
 </div>
@@ -871,15 +871,15 @@ <h3 class="callout-title">Initializing<a class="anchor" aria-label="anchor" href
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [...some test data...]</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb25-4"><a href="#cb25-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
-<span id="cb25-5"><a href="#cb25-5" aria-hidden="true" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
-<span id="cb25-6"><a href="#cb25-6" aria-hidden="true" tabindex="-1"></a>    ____:</span>
-<span id="cb25-7"><a href="#cb25-7" aria-hidden="true" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(____, v)</span>
-<span id="cb25-8"><a href="#cb25-8" aria-hidden="true" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(____, v)</span>
-<span id="cb25-9"><a href="#cb25-9" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a>values <span class="op">=</span> [...some test data...]</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb25-4"><a href="#cb25-4" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
+<span id="cb25-5"><a href="#cb25-5" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
+<span id="cb25-6"><a href="#cb25-6" tabindex="-1"></a>    ____:</span>
+<span id="cb25-7"><a href="#cb25-7" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(____, v)</span>
+<span id="cb25-8"><a href="#cb25-8" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(____, v)</span>
+<span id="cb25-9"><a href="#cb25-9" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 <p>What are the advantages and disadvantages of using this method to
 find the range of the data?</p>
@@ -896,15 +896,15 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">and</span> largest <span class="kw">is</span> <span class="va">None</span>:</span>
-<span id="cb26-5"><a href="#cb26-5" aria-hidden="true" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
-<span id="cb26-6"><a href="#cb26-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb26-7"><a href="#cb26-7" aria-hidden="true" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(smallest, v)</span>
-<span id="cb26-8"><a href="#cb26-8" aria-hidden="true" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(largest, v)</span>
-<span id="cb26-9"><a href="#cb26-9" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb26-4"><a href="#cb26-4" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">and</span> largest <span class="kw">is</span> <span class="va">None</span>:</span>
+<span id="cb26-5"><a href="#cb26-5" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
+<span id="cb26-6"><a href="#cb26-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb26-7"><a href="#cb26-7" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(smallest, v)</span>
+<span id="cb26-8"><a href="#cb26-8" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(largest, v)</span>
+<span id="cb26-9"><a href="#cb26-9" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 <p>If you wrote <code>== None</code> instead of <code>is None</code>,
 that works too, but Python programmers always write <code>is None</code>
@@ -918,14 +918,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
-<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb27-4"><a href="#cb27-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&lt;</span> smallest:</span>
-<span id="cb27-5"><a href="#cb27-5" aria-hidden="true" tabindex="-1"></a>        smallest <span class="op">=</span> v</span>
-<span id="cb27-6"><a href="#cb27-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> largest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&gt;</span> largest:</span>
-<span id="cb27-7"><a href="#cb27-7" aria-hidden="true" tabindex="-1"></a>        largest <span class="op">=</span> v</span>
-<span id="cb27-8"><a href="#cb27-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
+<span id="cb27-3"><a href="#cb27-3" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb27-4"><a href="#cb27-4" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&lt;</span> smallest:</span>
+<span id="cb27-5"><a href="#cb27-5" tabindex="-1"></a>        smallest <span class="op">=</span> v</span>
+<span id="cb27-6"><a href="#cb27-6" tabindex="-1"></a>    <span class="cf">if</span> largest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&gt;</span> largest:</span>
+<span id="cb27-7"><a href="#cb27-7" tabindex="-1"></a>        largest <span class="op">=</span> v</span>
+<span id="cb27-8"><a href="#cb27-8" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 <p>Now we have one loop, but four comparison tests. There are two ways
 we could improve it further: either use fewer comparisons in each
@@ -934,10 +934,10 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a>smallest <span class="op">=</span> <span class="bu">min</span>(values)</span>
-<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a>largest <span class="op">=</span> <span class="bu">max</span>(values)</span>
-<span id="cb28-4"><a href="#cb28-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a>smallest <span class="op">=</span> <span class="bu">min</span>(values)</span>
+<span id="cb28-3"><a href="#cb28-3" tabindex="-1"></a>largest <span class="op">=</span> <span class="bu">max</span>(values)</span>
+<span id="cb28-4"><a href="#cb28-4" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 </div>
 </div>
@@ -1022,7 +1022,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/13-conditionals.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2024-02-16",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/14-looping-data-sets.html b/14-looping-data-sets.html
index e68f7c61f..a3e444073 100644
--- a/14-looping-data-sets.html
+++ b/14-looping-data-sets.html
@@ -435,10 +435,10 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> [<span class="st">'data/gapminder_gdp_africa.csv'</span>, <span class="st">'data/gapminder_gdp_asia.csv'</span>]:</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(filename, data.<span class="bu">min</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> [<span class="st">'data/gapminder_gdp_africa.csv'</span>, <span class="st">'data/gapminder_gdp_asia.csv'</span>]:</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    <span class="bu">print</span>(filename, data.<span class="bu">min</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -484,8 +484,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all csv files in data directory:'</span>, glob.glob(<span class="st">'data/*.csv'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all csv files in data directory:'</span>, glob.glob(<span class="st">'data/*.csv'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -497,7 +497,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all PDB files:'</span>, glob.glob(<span class="st">'*.pdb'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all PDB files:'</span>, glob.glob(<span class="st">'*.pdb'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -512,9 +512,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_*.csv'</span>):</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(filename, data[<span class="st">'gdpPercap_1952'</span>].<span class="bu">min</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_*.csv'</span>):</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a>    <span class="bu">print</span>(filename, data[<span class="st">'gdpPercap_1952'</span>].<span class="bu">min</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -552,7 +552,7 @@ <h3 class="callout-title">Determining Matches<a class="anchor" aria-label="ancho
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>1 is not matched by the glob.</p>
 </div>
@@ -572,13 +572,13 @@ <h3 class="callout-title">Minimum File Size<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a>fewest <span class="op">=</span> ____</span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.____(filename)</span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(____, dataframe.shape[<span class="dv">0</span>])</span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a>fewest <span class="op">=</span> ____</span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.____(filename)</span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(____, dataframe.shape[<span class="dv">0</span>])</span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
 </div>
 <p>Note that the <a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.shape.html" class="external-link"><code>DataFrame.shape()</code>
 method</a> returns a tuple with the number of rows and columns of the
@@ -591,18 +591,18 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>fewest <span class="op">=</span> <span class="bu">float</span>(<span class="st">'Inf'</span>)</span>
-<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb10-5"><a href="#cb10-5" aria-hidden="true" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb10-6"><a href="#cb10-6" aria-hidden="true" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(fewest, dataframe.shape[<span class="dv">0</span>])</span>
-<span id="cb10-7"><a href="#cb10-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb10-3"><a href="#cb10-3" tabindex="-1"></a>fewest <span class="op">=</span> <span class="bu">float</span>(<span class="st">'Inf'</span>)</span>
+<span id="cb10-4"><a href="#cb10-4" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb10-5"><a href="#cb10-5" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb10-6"><a href="#cb10-6" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(fewest, dataframe.shape[<span class="dv">0</span>])</span>
+<span id="cb10-7"><a href="#cb10-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
 </div>
 <p>You might have chosen to initialize the <code>fewest</code> variable
 with a number greater than the numbers you’re dealing with, but that
@@ -632,7 +632,7 @@ <h3 class="callout-title">Comparing Data<a class="anchor" aria-label="anchor" hr
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>This solution builds a useful legend by using the <a href="https://docs.python.org/3/library/stdtypes.html#str.split" class="external-link">string
 <code>split</code> method</a> to extract the <code>region</code> from
@@ -640,32 +640,31 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span>
-<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a>fig, ax <span class="op">=</span> plt.subplots(<span class="dv">1</span>,<span class="dv">1</span>)</span>
-<span id="cb11-5"><a href="#cb11-5" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_gdp*.csv'</span>):</span>
-<span id="cb11-6"><a href="#cb11-6" aria-hidden="true" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb11-7"><a href="#cb11-7" aria-hidden="true" tabindex="-1"></a>    <span class="co"># extract &lt;region&gt; from the filename, expected to be in the format 'data/gapminder_gdp_&lt;region&gt;.csv'.</span></span>
-<span id="cb11-8"><a href="#cb11-8" aria-hidden="true" tabindex="-1"></a>    <span class="co"># we will split the string using the split method and `_` as our separator,</span></span>
-<span id="cb11-9"><a href="#cb11-9" aria-hidden="true" tabindex="-1"></a>    <span class="co"># retrieve the last string in the list that split returns (`&lt;region&gt;.csv`), </span></span>
-<span id="cb11-10"><a href="#cb11-10" aria-hidden="true" tabindex="-1"></a>    <span class="co"># and then remove the `.csv` extension from that string.</span></span>
-<span id="cb11-11"><a href="#cb11-11" aria-hidden="true" tabindex="-1"></a>    region <span class="op">=</span> filename.split(<span class="st">'_'</span>)[<span class="op">-</span><span class="dv">1</span>][:<span class="op">-</span><span class="dv">4</span>] </span>
-<span id="cb11-12"><a href="#cb11-12" aria-hidden="true" tabindex="-1"></a>    dataframe.mean().plot(ax<span class="op">=</span>ax, label<span class="op">=</span>region)</span>
-<span id="cb11-13"><a href="#cb11-13" aria-hidden="true" tabindex="-1"></a>plt.legend()</span>
-<span id="cb11-14"><a href="#cb11-14" aria-hidden="true" tabindex="-1"></a>plt.show()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span>
+<span id="cb11-4"><a href="#cb11-4" tabindex="-1"></a>fig, ax <span class="op">=</span> plt.subplots(<span class="dv">1</span>,<span class="dv">1</span>)</span>
+<span id="cb11-5"><a href="#cb11-5" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_gdp*.csv'</span>):</span>
+<span id="cb11-6"><a href="#cb11-6" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb11-7"><a href="#cb11-7" tabindex="-1"></a>    <span class="co"># extract &lt;region&gt; from the filename, expected to be in the format 'data/gapminder_gdp_&lt;region&gt;.csv'.</span></span>
+<span id="cb11-8"><a href="#cb11-8" tabindex="-1"></a>    <span class="co"># we will split the string using the split method and `_` as our separator,</span></span>
+<span id="cb11-9"><a href="#cb11-9" tabindex="-1"></a>    <span class="co"># retrieve the last string in the list that split returns (`&lt;region&gt;.csv`), </span></span>
+<span id="cb11-10"><a href="#cb11-10" tabindex="-1"></a>    <span class="co"># and then remove the `.csv` extension from that string.</span></span>
+<span id="cb11-11"><a href="#cb11-11" tabindex="-1"></a>    region <span class="op">=</span> filename.split(<span class="st">'_'</span>)[<span class="op">-</span><span class="dv">1</span>][:<span class="op">-</span><span class="dv">4</span>] </span>
+<span id="cb11-12"><a href="#cb11-12" tabindex="-1"></a>    dataframe.mean().plot(ax<span class="op">=</span>ax, label<span class="op">=</span>region)</span>
+<span id="cb11-13"><a href="#cb11-13" tabindex="-1"></a>plt.legend()</span>
+<span id="cb11-14"><a href="#cb11-14" tabindex="-1"></a>plt.show()</span></code></pre>
 </div>
 </div>
 </div>
 </div>
 </div>
-<div id="dealing-with-file-paths" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="dealing-with-file-paths" class="callout-inner">
-<h3 class="callout-title">Dealing with File Paths<a class="anchor" aria-label="anchor" href="#dealing-with-file-paths"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="dealing-with-file-paths">Dealing with File Paths<a class="anchor" aria-label="anchor" href="#dealing-with-file-paths"></a></h3>
 <div class="callout-content">
 <p>The <a href="https://docs.python.org/3/library/pathlib.html" class="external-link"><code>pathlib</code>
 module</a> provides useful abstractions for file and path manipulation
@@ -676,10 +675,10 @@ <h3 class="callout-title">Dealing with File Paths<a class="anchor" aria-label="a
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> pathlib <span class="im">import</span> Path</span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a>p <span class="op">=</span> Path(<span class="st">"data/gapminder_gdp_africa.csv"</span>)</span>
-<span id="cb12-4"><a href="#cb12-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(p.parent), <span class="bu">print</span>(p.stem), <span class="bu">print</span>(p.suffix)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="im">from</span> pathlib <span class="im">import</span> Path</span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a></span>
+<span id="cb12-3"><a href="#cb12-3" tabindex="-1"></a>p <span class="op">=</span> Path(<span class="st">"data/gapminder_gdp_africa.csv"</span>)</span>
+<span id="cb12-4"><a href="#cb12-4" tabindex="-1"></a><span class="bu">print</span>(p.parent), <span class="bu">print</span>(p.stem), <span class="bu">print</span>(p.suffix)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -770,7 +769,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/14-looping-data-sets.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/15-coffee.html b/15-coffee.html
index 7d57fb725..7bd9460b1 100644
--- a/15-coffee.html
+++ b/15-coffee.html
@@ -468,7 +468,7 @@ <h1>Afternoon Coffee</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/15-coffee.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/16-writing-functions.html b/16-writing-functions.html
index 0817214ab..f88dfce9b 100644
--- a/16-writing-functions.html
+++ b/16-writing-functions.html
@@ -463,10 +463,10 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_greeting():</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Hello!'</span>)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'The weather is nice today.'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Right?'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="kw">def</span> print_greeting():</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Hello!'</span>)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'The weather is nice today.'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Right?'</span>)</span></code></pre>
 </div>
 </section><section id="defining-a-function-does-not-run-it."><h2 class="section-heading">Defining a function does not run it.<a class="anchor" aria-label="anchor" href="#defining-a-function-does-not-run-it."></a>
 </h2>
@@ -477,7 +477,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a>print_greeting()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a>print_greeting()</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -500,11 +500,11 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-5"><a href="#cb4-5" aria-hidden="true" tabindex="-1"></a>print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
+<span id="cb4-3"><a href="#cb4-3" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span>
+<span id="cb4-4"><a href="#cb4-4" tabindex="-1"></a></span>
+<span id="cb4-5"><a href="#cb4-5" tabindex="-1"></a>print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -518,7 +518,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>print_date(month<span class="op">=</span><span class="dv">3</span>, day<span class="op">=</span><span class="dv">19</span>, year<span class="op">=</span><span class="dv">1871</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a>print_date(month<span class="op">=</span><span class="dv">3</span>, day<span class="op">=</span><span class="dv">19</span>, year<span class="op">=</span><span class="dv">1871</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -541,16 +541,16 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
-<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb8-3"><a href="#cb8-3" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
+<span id="cb8-4"><a href="#cb8-4" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">=</span> average([<span class="dv">1</span>, <span class="dv">3</span>, <span class="dv">4</span>])</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of actual values:'</span>, a)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>a <span class="op">=</span> average([<span class="dv">1</span>, <span class="dv">3</span>, <span class="dv">4</span>])</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of actual values:'</span>, a)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -560,7 +560,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of empty list:'</span>, average([]))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of empty list:'</span>, average([]))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -574,8 +574,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>result <span class="op">=</span> print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -600,10 +600,10 @@ <h3 class="callout-title">Identifying Syntax Errors<a class="anchor" aria-label=
 </ol><div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> another_function</span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a>   <span class="bu">print</span>(<span class="st">"But at least python tells us about them!"</span>)</span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="kw">def</span> another_function</span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a>   <span class="bu">print</span>(<span class="st">"But at least python tells us about them!"</span>)</span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -618,10 +618,10 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> another_function():</span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"But at least Python tells us about them!"</span>)</span>
-<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a><span class="kw">def</span> another_function():</span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"But at least Python tells us about them!"</span>)</span>
+<span id="cb16-4"><a href="#cb16-4" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -639,10 +639,10 @@ <h3 class="callout-title">Definition and Use<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> report(pressure):</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'pressure is'</span>, pressure)</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'calling'</span>, report, <span class="fl">22.5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="kw">def</span> report(pressure):</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'pressure is'</span>, pressure)</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a></span>
+<span id="cb17-4"><a href="#cb17-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'calling'</span>, report, <span class="fl">22.5</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -666,8 +666,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"calling"</span>)</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>report(<span class="fl">22.5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"calling"</span>)</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>report(<span class="fl">22.5</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -691,19 +691,19 @@ <h3 class="callout-title">Order of Operations<a class="anchor" aria-label="ancho
 </ol><div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_time(hour, minute, second):</span>
-<span id="cb21-4"><a href="#cb21-4" aria-hidden="true" tabindex="-1"></a>   time_string <span class="op">=</span> <span class="bu">str</span>(hour) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(minute) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(second)</span>
-<span id="cb21-5"><a href="#cb21-5" aria-hidden="true" tabindex="-1"></a>   <span class="bu">print</span>(time_string)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a></span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="kw">def</span> print_time(hour, minute, second):</span>
+<span id="cb21-4"><a href="#cb21-4" tabindex="-1"></a>   time_string <span class="op">=</span> <span class="bu">str</span>(hour) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(minute) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(second)</span>
+<span id="cb21-5"><a href="#cb21-5" tabindex="-1"></a>   <span class="bu">print</span>(time_string)</span></code></pre>
 </div>
 <ol start="2" style="list-style-type: decimal"><li>After fixing the problem above, explain why running this example
 code:</li>
 </ol><div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
 </div>
 <p>gives this output:</p>
 <div class="codewrapper">
@@ -754,11 +754,11 @@ <h3 class="callout-title">Encapsulation<a class="anchor" aria-label="anchor" hre
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> min_in_data(____):</span>
-<span id="cb24-4"><a href="#cb24-4" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> ____</span>
-<span id="cb24-5"><a href="#cb24-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> ____</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a></span>
+<span id="cb24-3"><a href="#cb24-3" tabindex="-1"></a><span class="kw">def</span> min_in_data(____):</span>
+<span id="cb24-4"><a href="#cb24-4" tabindex="-1"></a>    data <span class="op">=</span> ____</span>
+<span id="cb24-5"><a href="#cb24-5" tabindex="-1"></a>    <span class="cf">return</span> ____</span></code></pre>
 </div>
 </div>
 </div>
@@ -773,11 +773,11 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> min_in_data(filename):</span>
-<span id="cb25-4"><a href="#cb25-4" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb25-5"><a href="#cb25-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> data.<span class="bu">min</span>()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a></span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a><span class="kw">def</span> min_in_data(filename):</span>
+<span id="cb25-4"><a href="#cb25-4" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb25-5"><a href="#cb25-5" tabindex="-1"></a>    <span class="cf">return</span> data.<span class="bu">min</span>()</span></code></pre>
 </div>
 </div>
 </div>
@@ -798,10 +798,10 @@ <h3 class="callout-title">Find the First<a class="anchor" aria-label="anchor" hr
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> ____:</span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> ____:</span>
-<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a>            <span class="cf">return</span> ____</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> ____:</span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a>        <span class="cf">if</span> ____:</span>
+<span id="cb26-4"><a href="#cb26-4" tabindex="-1"></a>            <span class="cf">return</span> ____</span></code></pre>
 </div>
 </div>
 </div>
@@ -816,18 +816,18 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> v <span class="op">&lt;</span> <span class="dv">0</span>:</span>
-<span id="cb27-4"><a href="#cb27-4" aria-hidden="true" tabindex="-1"></a>            <span class="cf">return</span> v</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb27-3"><a href="#cb27-3" tabindex="-1"></a>        <span class="cf">if</span> v <span class="op">&lt;</span> <span class="dv">0</span>:</span>
+<span id="cb27-4"><a href="#cb27-4" tabindex="-1"></a>            <span class="cf">return</span> v</span></code></pre>
 </div>
 <p>If an empty list or a list with all positive values is passed to this
 function, it returns <code>None</code>:</p>
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>my_list <span class="op">=</span> []</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(first_negative(my_list))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>my_list <span class="op">=</span> []</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a><span class="bu">print</span>(first_negative(my_list))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -850,16 +850,16 @@ <h3 class="callout-title">Calling by Name<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
-<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
-<span id="cb30-3"><a href="#cb30-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
+<span id="cb30-2"><a href="#cb30-2" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
+<span id="cb30-3"><a href="#cb30-3" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span></code></pre>
 </div>
 <p>We saw that we can call the function using <em>named arguments</em>,
 like this:</p>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>print_date(day<span class="op">=</span><span class="dv">1</span>, month<span class="op">=</span><span class="dv">2</span>, year<span class="op">=</span><span class="dv">2003</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>print_date(day<span class="op">=</span><span class="dv">1</span>, month<span class="op">=</span><span class="dv">2</span>, year<span class="op">=</span><span class="dv">2003</span>)</span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>What does <code>print_date(day=1, month=2, year=2003)</code>
 print?</li>
@@ -903,24 +903,24 @@ <h3 class="callout-title">Encapsulation of an If/Print Block<a class="anchor" ar
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb32-2"><a href="#cb32-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb32-3"><a href="#cb32-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb32-4"><a href="#cb32-4" aria-hidden="true" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
-<span id="cb32-5"><a href="#cb32-5" aria-hidden="true" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
-<span id="cb32-6"><a href="#cb32-6" aria-hidden="true" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
-<span id="cb32-7"><a href="#cb32-7" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb32-8"><a href="#cb32-8" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(mass)</span>
-<span id="cb32-9"><a href="#cb32-9" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb32-10"><a href="#cb32-10" aria-hidden="true" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
-<span id="cb32-11"><a href="#cb32-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
-<span id="cb32-12"><a href="#cb32-12" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"jumbo"</span>)</span>
-<span id="cb32-13"><a href="#cb32-13" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
-<span id="cb32-14"><a href="#cb32-14" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"large"</span>)</span>
-<span id="cb32-15"><a href="#cb32-15" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
-<span id="cb32-16"><a href="#cb32-16" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"medium"</span>)</span>
-<span id="cb32-17"><a href="#cb32-17" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb32-18"><a href="#cb32-18" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"small"</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb32-2"><a href="#cb32-2" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb32-3"><a href="#cb32-3" tabindex="-1"></a></span>
+<span id="cb32-4"><a href="#cb32-4" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
+<span id="cb32-5"><a href="#cb32-5" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
+<span id="cb32-6"><a href="#cb32-6" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
+<span id="cb32-7"><a href="#cb32-7" tabindex="-1"></a></span>
+<span id="cb32-8"><a href="#cb32-8" tabindex="-1"></a>    <span class="bu">print</span>(mass)</span>
+<span id="cb32-9"><a href="#cb32-9" tabindex="-1"></a></span>
+<span id="cb32-10"><a href="#cb32-10" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
+<span id="cb32-11"><a href="#cb32-11" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
+<span id="cb32-12"><a href="#cb32-12" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"jumbo"</span>)</span>
+<span id="cb32-13"><a href="#cb32-13" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
+<span id="cb32-14"><a href="#cb32-14" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"large"</span>)</span>
+<span id="cb32-15"><a href="#cb32-15" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
+<span id="cb32-16"><a href="#cb32-16" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"medium"</span>)</span>
+<span id="cb32-17"><a href="#cb32-17" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb32-18"><a href="#cb32-18" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"small"</span>)</span></code></pre>
 </div>
 <p>The if-block that classifies the eggs might be useful in other
 situations, so to avoid repeating it, we could fold it into a function,
@@ -929,15 +929,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb33">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a><span class="co"># revised version</span></span>
-<span id="cb33-2"><a href="#cb33-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb33-3"><a href="#cb33-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb33-4"><a href="#cb33-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb33-5"><a href="#cb33-5" aria-hidden="true" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
-<span id="cb33-6"><a href="#cb33-6" aria-hidden="true" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
-<span id="cb33-7"><a href="#cb33-7" aria-hidden="true" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
-<span id="cb33-8"><a href="#cb33-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb33-9"><a href="#cb33-9" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(mass, get_egg_label(mass))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" tabindex="-1"></a><span class="co"># revised version</span></span>
+<span id="cb33-2"><a href="#cb33-2" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb33-3"><a href="#cb33-3" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb33-4"><a href="#cb33-4" tabindex="-1"></a></span>
+<span id="cb33-5"><a href="#cb33-5" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
+<span id="cb33-6"><a href="#cb33-6" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
+<span id="cb33-7"><a href="#cb33-7" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
+<span id="cb33-8"><a href="#cb33-8" tabindex="-1"></a></span>
+<span id="cb33-9"><a href="#cb33-9" tabindex="-1"></a>    <span class="bu">print</span>(mass, get_egg_label(mass))</span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>Create a function definition for <code>get_egg_label()</code> that
 will work with the revised program above. Note that the
@@ -962,22 +962,22 @@ <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> get_egg_label(mass):</span>
-<span id="cb34-2"><a href="#cb34-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
-<span id="cb34-3"><a href="#cb34-3" aria-hidden="true" tabindex="-1"></a>    egg_label <span class="op">=</span> <span class="st">"Unlabelled"</span></span>
-<span id="cb34-4"><a href="#cb34-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
-<span id="cb34-5"><a href="#cb34-5" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"warning: egg might be dirty"</span></span>
-<span id="cb34-6"><a href="#cb34-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
-<span id="cb34-7"><a href="#cb34-7" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"jumbo"</span></span>
-<span id="cb34-8"><a href="#cb34-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
-<span id="cb34-9"><a href="#cb34-9" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"large"</span></span>
-<span id="cb34-10"><a href="#cb34-10" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
-<span id="cb34-11"><a href="#cb34-11" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"medium"</span></span>
-<span id="cb34-12"><a href="#cb34-12" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">50</span>:</span>
-<span id="cb34-13"><a href="#cb34-13" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"too light, probably spoiled"</span></span>
-<span id="cb34-14"><a href="#cb34-14" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb34-15"><a href="#cb34-15" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"small"</span></span>
-<span id="cb34-16"><a href="#cb34-16" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> egg_label</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a><span class="kw">def</span> get_egg_label(mass):</span>
+<span id="cb34-2"><a href="#cb34-2" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
+<span id="cb34-3"><a href="#cb34-3" tabindex="-1"></a>    egg_label <span class="op">=</span> <span class="st">"Unlabelled"</span></span>
+<span id="cb34-4"><a href="#cb34-4" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
+<span id="cb34-5"><a href="#cb34-5" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"warning: egg might be dirty"</span></span>
+<span id="cb34-6"><a href="#cb34-6" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
+<span id="cb34-7"><a href="#cb34-7" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"jumbo"</span></span>
+<span id="cb34-8"><a href="#cb34-8" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
+<span id="cb34-9"><a href="#cb34-9" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"large"</span></span>
+<span id="cb34-10"><a href="#cb34-10" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
+<span id="cb34-11"><a href="#cb34-11" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"medium"</span></span>
+<span id="cb34-12"><a href="#cb34-12" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">50</span>:</span>
+<span id="cb34-13"><a href="#cb34-13" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"too light, probably spoiled"</span></span>
+<span id="cb34-14"><a href="#cb34-14" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb34-15"><a href="#cb34-15" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"small"</span></span>
+<span id="cb34-16"><a href="#cb34-16" tabindex="-1"></a>    <span class="cf">return</span> egg_label</span></code></pre>
 </div>
 </div>
 </div>
@@ -995,30 +995,30 @@ <h3 class="callout-title">Encapsulating Data Analysis<a class="anchor" aria-labe
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb35-2"><a href="#cb35-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb35-3"><a href="#cb35-3" aria-hidden="true" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb35-4"><a href="#cb35-4" aria-hidden="true" tabindex="-1"></a>japan <span class="op">=</span> data_asia.loc[<span class="st">'Japan'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb35-2"><a href="#cb35-2" tabindex="-1"></a></span>
+<span id="cb35-3"><a href="#cb35-3" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb35-4"><a href="#cb35-4" tabindex="-1"></a>japan <span class="op">=</span> data_asia.loc[<span class="st">'Japan'</span>]</span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>Complete the statements below to obtain the average GDP for Japan
 across the years reported for the 1980s.</li>
 </ol><div class="codewrapper sourceCode" id="cb36">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" aria-hidden="true" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
-<span id="cb36-2"><a href="#cb36-2" aria-hidden="true" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> ____)</span>
-<span id="cb36-3"><a href="#cb36-3" aria-hidden="true" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> ___] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> ___]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
+<span id="cb36-2"><a href="#cb36-2" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> ____)</span>
+<span id="cb36-3"><a href="#cb36-3" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> ___] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> ___]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
 </div>
 <ol start="2" style="list-style-type: decimal"><li>Abstract the code above into a single function.</li>
 </ol><div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
-<span id="cb37-2"><a href="#cb37-2" aria-hidden="true" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span><span class="op">+</span>___<span class="op">+</span><span class="st">'.csv'</span>,delimiter<span class="op">=</span><span class="st">','</span>,index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb37-3"><a href="#cb37-3" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb37-4"><a href="#cb37-4" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb37-5"><a href="#cb37-5" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb37-6"><a href="#cb37-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
+<span id="cb37-2"><a href="#cb37-2" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span><span class="op">+</span>___<span class="op">+</span><span class="st">'.csv'</span>,delimiter<span class="op">=</span><span class="st">','</span>,index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb37-3"><a href="#cb37-3" tabindex="-1"></a>    ____</span>
+<span id="cb37-4"><a href="#cb37-4" tabindex="-1"></a>    ____</span>
+<span id="cb37-5"><a href="#cb37-5" tabindex="-1"></a>    ____</span>
+<span id="cb37-6"><a href="#cb37-6" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
 </div>
 <ol start="3" style="list-style-type: decimal"><li>How would you generalize this function if you did not know
 beforehand which specific years occurred as columns in the data? For
@@ -1040,43 +1040,43 @@ <h4 class="accordion-header" id="headingSolution8">Show me the solution</h4>
 </ol><div class="codewrapper sourceCode" id="cb38">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
-<span id="cb38-2"><a href="#cb38-2" aria-hidden="true" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
-<span id="cb38-3"><a href="#cb38-3" aria-hidden="true" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
+<span id="cb38-2"><a href="#cb38-2" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
+<span id="cb38-3"><a href="#cb38-3" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
 </div>
 <ol start="2" style="list-style-type: decimal"><li>That code as a function is:</li>
 </ol><div class="codewrapper sourceCode" id="cb39">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
-<span id="cb39-2"><a href="#cb39-2" aria-hidden="true" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb39-3"><a href="#cb39-3" aria-hidden="true" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
-<span id="cb39-4"><a href="#cb39-4" aria-hidden="true" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
-<span id="cb39-5"><a href="#cb39-5" aria-hidden="true" tabindex="-1"></a>    avg <span class="op">=</span> (c.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> c.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>])<span class="op">/</span><span class="dv">2</span></span>
-<span id="cb39-6"><a href="#cb39-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
+<span id="cb39-2"><a href="#cb39-2" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb39-3"><a href="#cb39-3" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
+<span id="cb39-4"><a href="#cb39-4" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
+<span id="cb39-5"><a href="#cb39-5" tabindex="-1"></a>    avg <span class="op">=</span> (c.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> c.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>])<span class="op">/</span><span class="dv">2</span></span>
+<span id="cb39-6"><a href="#cb39-6" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
 </div>
 <ol start="3" style="list-style-type: decimal"><li>To obtain the average for the relevant years, we need to loop over
 them:</li>
 </ol><div class="codewrapper sourceCode" id="cb40">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
-<span id="cb40-2"><a href="#cb40-2" aria-hidden="true" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb40-3"><a href="#cb40-3" aria-hidden="true" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
-<span id="cb40-4"><a href="#cb40-4" aria-hidden="true" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
-<span id="cb40-5"><a href="#cb40-5" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> <span class="fl">0.0</span></span>
-<span id="cb40-6"><a href="#cb40-6" aria-hidden="true" tabindex="-1"></a>    num_years <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb40-7"><a href="#cb40-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> yr_header <span class="kw">in</span> c.index: <span class="co"># c's index contains reported years</span></span>
-<span id="cb40-8"><a href="#cb40-8" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> yr_header.startswith(gdp_decade):</span>
-<span id="cb40-9"><a href="#cb40-9" aria-hidden="true" tabindex="-1"></a>            total <span class="op">=</span> total <span class="op">+</span> c.loc[yr_header]</span>
-<span id="cb40-10"><a href="#cb40-10" aria-hidden="true" tabindex="-1"></a>            num_years <span class="op">=</span> num_years <span class="op">+</span> <span class="dv">1</span></span>
-<span id="cb40-11"><a href="#cb40-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> total<span class="op">/</span>num_years</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
+<span id="cb40-2"><a href="#cb40-2" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb40-3"><a href="#cb40-3" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
+<span id="cb40-4"><a href="#cb40-4" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
+<span id="cb40-5"><a href="#cb40-5" tabindex="-1"></a>    total <span class="op">=</span> <span class="fl">0.0</span></span>
+<span id="cb40-6"><a href="#cb40-6" tabindex="-1"></a>    num_years <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb40-7"><a href="#cb40-7" tabindex="-1"></a>    <span class="cf">for</span> yr_header <span class="kw">in</span> c.index: <span class="co"># c's index contains reported years</span></span>
+<span id="cb40-8"><a href="#cb40-8" tabindex="-1"></a>        <span class="cf">if</span> yr_header.startswith(gdp_decade):</span>
+<span id="cb40-9"><a href="#cb40-9" tabindex="-1"></a>            total <span class="op">=</span> total <span class="op">+</span> c.loc[yr_header]</span>
+<span id="cb40-10"><a href="#cb40-10" tabindex="-1"></a>            num_years <span class="op">=</span> num_years <span class="op">+</span> <span class="dv">1</span></span>
+<span id="cb40-11"><a href="#cb40-11" tabindex="-1"></a>    <span class="cf">return</span> total<span class="op">/</span>num_years</span></code></pre>
 </div>
 <p>The function can now be called by:</p>
 <div class="codewrapper sourceCode" id="cb41">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" aria-hidden="true" tabindex="-1"></a>avg_gdp_in_decade(<span class="st">'Japan'</span>,<span class="st">'asia'</span>,<span class="dv">1983</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" tabindex="-1"></a>avg_gdp_in_decade(<span class="st">'Japan'</span>,<span class="st">'asia'</span>,<span class="dv">1983</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1137,18 +1137,18 @@ <h4 class="accordion-header" id="headingSolution9">Show me the solution</h4>
 <ol style="list-style-type: decimal"><li><div class="codewrapper sourceCode" id="cb43">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a>  <span class="kw">def</span> logistic_map(x, r):</span>
-<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a>      <span class="cf">return</span> r <span class="op">*</span> x <span class="op">*</span> (<span class="dv">1</span> <span class="op">-</span> x)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" tabindex="-1"></a>  <span class="kw">def</span> logistic_map(x, r):</span>
+<span id="cb43-2"><a href="#cb43-2" tabindex="-1"></a>      <span class="cf">return</span> r <span class="op">*</span> x <span class="op">*</span> (<span class="dv">1</span> <span class="op">-</span> x)</span></code></pre>
 </div></li>
 <li><div class="codewrapper sourceCode" id="cb44">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" aria-hidden="true" tabindex="-1"></a>  initial_population <span class="op">=</span> <span class="fl">0.5</span></span>
-<span id="cb44-2"><a href="#cb44-2" aria-hidden="true" tabindex="-1"></a>  t_final <span class="op">=</span> <span class="dv">10</span></span>
-<span id="cb44-3"><a href="#cb44-3" aria-hidden="true" tabindex="-1"></a>  r <span class="op">=</span> <span class="fl">1.0</span></span>
-<span id="cb44-4"><a href="#cb44-4" aria-hidden="true" tabindex="-1"></a>  population <span class="op">=</span> [initial_population]</span>
-<span id="cb44-5"><a href="#cb44-5" aria-hidden="true" tabindex="-1"></a>  <span class="cf">for</span> t <span class="kw">in</span> <span class="bu">range</span>(t_final):</span>
-<span id="cb44-6"><a href="#cb44-6" aria-hidden="true" tabindex="-1"></a>      population.append( logistic_map(population[t], r) )</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" tabindex="-1"></a>  initial_population <span class="op">=</span> <span class="fl">0.5</span></span>
+<span id="cb44-2"><a href="#cb44-2" tabindex="-1"></a>  t_final <span class="op">=</span> <span class="dv">10</span></span>
+<span id="cb44-3"><a href="#cb44-3" tabindex="-1"></a>  r <span class="op">=</span> <span class="fl">1.0</span></span>
+<span id="cb44-4"><a href="#cb44-4" tabindex="-1"></a>  population <span class="op">=</span> [initial_population]</span>
+<span id="cb44-5"><a href="#cb44-5" tabindex="-1"></a>  <span class="cf">for</span> t <span class="kw">in</span> <span class="bu">range</span>(t_final):</span>
+<span id="cb44-6"><a href="#cb44-6" tabindex="-1"></a>      population.append( logistic_map(population[t], r) )</span></code></pre>
 </div></li>
 <li>```python def iterate(initial_population, t_final, r): population =
 [initial_population] for t in range(t_final): population.append(
@@ -1167,14 +1167,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </div>
 </div>
 </div>
-<div id="using-functions-with-conditionals-in-pandas" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="using-functions-with-conditionals-in-pandas" class="callout-inner">
-<h3 class="callout-title">Using Functions With Conditionals in
-Pandas<a class="anchor" aria-label="anchor" href="#using-functions-with-conditionals-in-pandas"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="using-functions-with-conditionals-in-pandas">Using Functions With Conditionals in
+Pandas<a class="anchor" aria-label="anchor" href="#using-functions-with-conditionals-in-pandas"></a></h3>
 <div class="callout-content">
 <p>Functions will often contain conditionals. Here is a short example
 that will indicate which quartile the argument is in based on hand-coded
@@ -1182,24 +1181,24 @@ <h3 class="callout-title">Using Functions With Conditionals in
 <div class="codewrapper sourceCode" id="cb46">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> calculate_life_quartile(exp):</span>
-<span id="cb46-2"><a href="#cb46-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> exp <span class="op">&lt;</span> <span class="fl">58.41</span>:</span>
-<span id="cb46-3"><a href="#cb46-3" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the first quartile</span></span>
-<span id="cb46-4"><a href="#cb46-4" aria-hidden="true" tabindex="-1"></a>        <span class="cf">return</span> <span class="dv">1</span></span>
-<span id="cb46-5"><a href="#cb46-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">58.41</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">67.05</span>:</span>
-<span id="cb46-6"><a href="#cb46-6" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the second quartile</span></span>
-<span id="cb46-7"><a href="#cb46-7" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">2</span></span>
-<span id="cb46-8"><a href="#cb46-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">67.05</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">71.70</span>:</span>
-<span id="cb46-9"><a href="#cb46-9" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the third quartile</span></span>
-<span id="cb46-10"><a href="#cb46-10" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">3</span></span>
-<span id="cb46-11"><a href="#cb46-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">71.70</span>:</span>
-<span id="cb46-12"><a href="#cb46-12" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the fourth quartile</span></span>
-<span id="cb46-13"><a href="#cb46-13" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">4</span></span>
-<span id="cb46-14"><a href="#cb46-14" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb46-15"><a href="#cb46-15" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation has bad data</span></span>
-<span id="cb46-16"><a href="#cb46-16" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="va">None</span></span>
-<span id="cb46-17"><a href="#cb46-17" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb46-18"><a href="#cb46-18" aria-hidden="true" tabindex="-1"></a>calculate_life_quartile(<span class="fl">62.5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" tabindex="-1"></a><span class="kw">def</span> calculate_life_quartile(exp):</span>
+<span id="cb46-2"><a href="#cb46-2" tabindex="-1"></a>    <span class="cf">if</span> exp <span class="op">&lt;</span> <span class="fl">58.41</span>:</span>
+<span id="cb46-3"><a href="#cb46-3" tabindex="-1"></a>        <span class="co"># This observation is in the first quartile</span></span>
+<span id="cb46-4"><a href="#cb46-4" tabindex="-1"></a>        <span class="cf">return</span> <span class="dv">1</span></span>
+<span id="cb46-5"><a href="#cb46-5" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">58.41</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">67.05</span>:</span>
+<span id="cb46-6"><a href="#cb46-6" tabindex="-1"></a>        <span class="co"># This observation is in the second quartile</span></span>
+<span id="cb46-7"><a href="#cb46-7" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">2</span></span>
+<span id="cb46-8"><a href="#cb46-8" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">67.05</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">71.70</span>:</span>
+<span id="cb46-9"><a href="#cb46-9" tabindex="-1"></a>        <span class="co"># This observation is in the third quartile</span></span>
+<span id="cb46-10"><a href="#cb46-10" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">3</span></span>
+<span id="cb46-11"><a href="#cb46-11" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">71.70</span>:</span>
+<span id="cb46-12"><a href="#cb46-12" tabindex="-1"></a>        <span class="co"># This observation is in the fourth quartile</span></span>
+<span id="cb46-13"><a href="#cb46-13" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">4</span></span>
+<span id="cb46-14"><a href="#cb46-14" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb46-15"><a href="#cb46-15" tabindex="-1"></a>        <span class="co"># This observation has bad data</span></span>
+<span id="cb46-16"><a href="#cb46-16" tabindex="-1"></a>       <span class="cf">return</span> <span class="va">None</span></span>
+<span id="cb46-17"><a href="#cb46-17" tabindex="-1"></a></span>
+<span id="cb46-18"><a href="#cb46-18" tabindex="-1"></a>calculate_life_quartile(<span class="fl">62.5</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1213,8 +1212,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb48">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>)</span>
-<span id="cb48-2"><a href="#cb48-2" aria-hidden="true" tabindex="-1"></a>data[<span class="st">'life_qrtl'</span>] <span class="op">=</span> data[<span class="st">'lifeExp_1952'</span>].<span class="bu">apply</span>(calculate_life_quartile)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>)</span>
+<span id="cb48-2"><a href="#cb48-2" tabindex="-1"></a>data[<span class="st">'life_qrtl'</span>] <span class="op">=</span> data[<span class="st">'lifeExp_1952'</span>].<span class="bu">apply</span>(calculate_life_quartile)</span></code></pre>
 </div>
 <p>There is a lot in that second line, so let’s take it piece by piece.
 On the right side of the <code>=</code> we start with
@@ -1305,7 +1304,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/16-writing-functions.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-07-24",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/17-scope.html b/17-scope.html
index 73e587467..6c35149c7 100644
--- a/17-scope.html
+++ b/17-scope.html
@@ -437,11 +437,11 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">103.9</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> adjust(t):</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    temperature <span class="op">=</span> t <span class="op">*</span> <span class="fl">1.43</span> <span class="op">/</span> pressure</span>
-<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> temperature</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">103.9</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="kw">def</span> adjust(t):</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    temperature <span class="op">=</span> t <span class="op">*</span> <span class="fl">1.43</span> <span class="op">/</span> pressure</span>
+<span id="cb1-5"><a href="#cb1-5" tabindex="-1"></a>    <span class="cf">return</span> temperature</span></code></pre>
 </div>
 <ul><li>
 <code>pressure</code> is a <em>global variable</em>.
@@ -459,8 +459,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'adjusted:'</span>, adjust(<span class="fl">0.9</span>))</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'temperature after call:'</span>, temperature)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'adjusted:'</span>, adjust(<span class="fl">0.9</span>))</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'temperature after call:'</span>, temperature)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -488,13 +488,13 @@ <h3 class="callout-title">Local and Global Variable Use<a class="anchor" aria-la
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>limit <span class="op">=</span> <span class="dv">100</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> clip(value):</span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">min</span>(<span class="bu">max</span>(<span class="fl">0.0</span>, value), limit)</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a>value <span class="op">=</span> <span class="op">-</span><span class="fl">22.5</span></span>
-<span id="cb5-7"><a href="#cb5-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(clip(value))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>limit <span class="op">=</span> <span class="dv">100</span></span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a></span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a><span class="kw">def</span> clip(value):</span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">min</span>(<span class="bu">max</span>(<span class="fl">0.0</span>, value), limit)</span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a></span>
+<span id="cb5-6"><a href="#cb5-6" tabindex="-1"></a>value <span class="op">=</span> <span class="op">-</span><span class="fl">22.5</span></span>
+<span id="cb5-7"><a href="#cb5-7" tabindex="-1"></a><span class="bu">print</span>(clip(value))</span></code></pre>
 </div>
 </div>
 </div>
@@ -545,7 +545,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <ol style="list-style-type: decimal"><li>Three levels.</li>
 <li><code>errors_02.py</code></li>
@@ -634,7 +634,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/17-scope.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/18-style.html b/18-style.html
index ce3502e53..602efe868 100644
--- a/18-style.html
+++ b/18-style.html
@@ -472,10 +472,10 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> calc_bulk_density(mass, volume):</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">'''Return dry bulk density = powder mass / powder volume.'''</span></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">assert</span> volume <span class="op">&gt;</span> <span class="dv">0</span></span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> mass <span class="op">/</span> volume</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="kw">def</span> calc_bulk_density(mass, volume):</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>    <span class="co">'''Return dry bulk density = powder mass / powder volume.'''</span></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    <span class="cf">assert</span> volume <span class="op">&gt;</span> <span class="dv">0</span></span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    <span class="cf">return</span> mass <span class="op">/</span> volume</span></code></pre>
 </div>
 <p>If the assertion is <code>False</code>, the Python interpreter raises
 an <code>AssertionError</code> runtime exception. The source code for
@@ -493,14 +493,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">"Return average of values, or None if no values are supplied."</span></span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
-<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span>
-<span id="cb2-7"><a href="#cb2-7" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb2-8"><a href="#cb2-8" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(average)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a>    <span class="co">"Return average of values, or None if no values are supplied."</span></span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a></span>
+<span id="cb2-4"><a href="#cb2-4" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb2-5"><a href="#cb2-5" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
+<span id="cb2-6"><a href="#cb2-6" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span>
+<span id="cb2-7"><a href="#cb2-7" tabindex="-1"></a></span>
+<span id="cb2-8"><a href="#cb2-8" tabindex="-1"></a><span class="bu">help</span>(average)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -510,13 +510,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 average(values)
     Return average of values, or None if no values are supplied.</code></pre>
 </div>
-<div id="multiline-strings" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="multiline-strings" class="callout-inner">
-<h3 class="callout-title">Multiline Strings<a class="anchor" aria-label="anchor" href="#multiline-strings"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="multiline-strings">Multiline Strings<a class="anchor" aria-label="anchor" href="#multiline-strings"></a></h3>
 <div class="callout-content">
 <p>Often use <em>multiline strings</em> for documentation. These start
 and end with three quote characters (either single or double) and end
@@ -524,10 +523,10 @@ <h3 class="callout-title">Multiline Strings<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="co">"""This string spans</span></span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="co">multiple lines.</span></span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a><span class="co">Blank lines are allowed."""</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="co">"""This string spans</span></span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a><span class="co">multiple lines.</span></span>
+<span id="cb4-3"><a href="#cb4-3" tabindex="-1"></a></span>
+<span id="cb4-4"><a href="#cb4-4" tabindex="-1"></a><span class="co">Blank lines are allowed."""</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -546,22 +545,22 @@ <h3 class="callout-title">What Will Be Shown?<a class="anchor" aria-label="ancho
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="co">"Find maximum edit distance between multiple sequences."</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="co"># This finds the maximum distance between all sequences.</span></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> overall_max(sequences):</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>    <span class="co">'''Determine overall maximum edit distance.'''</span></span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-7"><a href="#cb5-7" aria-hidden="true" tabindex="-1"></a>    highest <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb5-8"><a href="#cb5-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> left <span class="kw">in</span> sequences:</span>
-<span id="cb5-9"><a href="#cb5-9" aria-hidden="true" tabindex="-1"></a>        <span class="cf">for</span> right <span class="kw">in</span> sequences:</span>
-<span id="cb5-10"><a href="#cb5-10" aria-hidden="true" tabindex="-1"></a>            <span class="co">'''Avoid checking sequence against itself.'''</span></span>
-<span id="cb5-11"><a href="#cb5-11" aria-hidden="true" tabindex="-1"></a>            <span class="cf">if</span> left <span class="op">!=</span> right:</span>
-<span id="cb5-12"><a href="#cb5-12" aria-hidden="true" tabindex="-1"></a>                this <span class="op">=</span> edit_distance(left, right)</span>
-<span id="cb5-13"><a href="#cb5-13" aria-hidden="true" tabindex="-1"></a>                highest <span class="op">=</span> <span class="bu">max</span>(highest, this)</span>
-<span id="cb5-14"><a href="#cb5-14" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-15"><a href="#cb5-15" aria-hidden="true" tabindex="-1"></a>    <span class="co"># Report.</span></span>
-<span id="cb5-16"><a href="#cb5-16" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> highest</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="co">"Find maximum edit distance between multiple sequences."</span></span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="co"># This finds the maximum distance between all sequences.</span></span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a></span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a><span class="kw">def</span> overall_max(sequences):</span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a>    <span class="co">'''Determine overall maximum edit distance.'''</span></span>
+<span id="cb5-6"><a href="#cb5-6" tabindex="-1"></a></span>
+<span id="cb5-7"><a href="#cb5-7" tabindex="-1"></a>    highest <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb5-8"><a href="#cb5-8" tabindex="-1"></a>    <span class="cf">for</span> left <span class="kw">in</span> sequences:</span>
+<span id="cb5-9"><a href="#cb5-9" tabindex="-1"></a>        <span class="cf">for</span> right <span class="kw">in</span> sequences:</span>
+<span id="cb5-10"><a href="#cb5-10" tabindex="-1"></a>            <span class="co">'''Avoid checking sequence against itself.'''</span></span>
+<span id="cb5-11"><a href="#cb5-11" tabindex="-1"></a>            <span class="cf">if</span> left <span class="op">!=</span> right:</span>
+<span id="cb5-12"><a href="#cb5-12" tabindex="-1"></a>                this <span class="op">=</span> edit_distance(left, right)</span>
+<span id="cb5-13"><a href="#cb5-13" tabindex="-1"></a>                highest <span class="op">=</span> <span class="bu">max</span>(highest, this)</span>
+<span id="cb5-14"><a href="#cb5-14" tabindex="-1"></a></span>
+<span id="cb5-15"><a href="#cb5-15" tabindex="-1"></a>    <span class="co"># Report.</span></span>
+<span id="cb5-16"><a href="#cb5-16" tabindex="-1"></a>    <span class="cf">return</span> highest</span></code></pre>
 </div>
 </div>
 </div>
@@ -587,12 +586,12 @@ <h3 class="callout-title">Document This<a class="anchor" aria-label="anchor" hre
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># Return the middle value of three.</span></span>
-<span id="cb6-3"><a href="#cb6-3" aria-hidden="true" tabindex="-1"></a>    <span class="co"># Assumes the values can actually be compared.</span></span>
-<span id="cb6-4"><a href="#cb6-4" aria-hidden="true" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
-<span id="cb6-5"><a href="#cb6-5" aria-hidden="true" tabindex="-1"></a>    values.sort()</span>
-<span id="cb6-6"><a href="#cb6-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
+<span id="cb6-2"><a href="#cb6-2" tabindex="-1"></a>    <span class="co"># Return the middle value of three.</span></span>
+<span id="cb6-3"><a href="#cb6-3" tabindex="-1"></a>    <span class="co"># Assumes the values can actually be compared.</span></span>
+<span id="cb6-4"><a href="#cb6-4" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
+<span id="cb6-5"><a href="#cb6-5" tabindex="-1"></a>    values.sort()</span>
+<span id="cb6-6"><a href="#cb6-6" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -602,17 +601,17 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">'''Return the middle value of three.</span></span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a><span class="co">    Assumes the values can actually be compared.'''</span></span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
-<span id="cb7-5"><a href="#cb7-5" aria-hidden="true" tabindex="-1"></a>    values.sort()</span>
-<span id="cb7-6"><a href="#cb7-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>    <span class="co">'''Return the middle value of three.</span></span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a><span class="co">    Assumes the values can actually be compared.'''</span></span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
+<span id="cb7-5"><a href="#cb7-5" tabindex="-1"></a>    values.sort()</span>
+<span id="cb7-6"><a href="#cb7-6" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -635,21 +634,21 @@ <h3 class="callout-title">Clean Up This Code<a class="anchor" aria-label="anchor
 </ol><div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a>n <span class="op">=</span> <span class="dv">10</span></span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>s <span class="op">=</span> <span class="st">'et cetera'</span></span>
-<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(s)</span>
-<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb8-5"><a href="#cb8-5" aria-hidden="true" tabindex="-1"></a><span class="cf">while</span> i <span class="op">&lt;</span> n:</span>
-<span id="cb8-6"><a href="#cb8-6" aria-hidden="true" tabindex="-1"></a>    <span class="co"># print('at', j)</span></span>
-<span id="cb8-7"><a href="#cb8-7" aria-hidden="true" tabindex="-1"></a>    new <span class="op">=</span> <span class="st">''</span></span>
-<span id="cb8-8"><a href="#cb8-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(<span class="bu">len</span>(s)):</span>
-<span id="cb8-9"><a href="#cb8-9" aria-hidden="true" tabindex="-1"></a>        left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
-<span id="cb8-10"><a href="#cb8-10" aria-hidden="true" tabindex="-1"></a>        right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>)<span class="op">%</span><span class="bu">len</span>(s)</span>
-<span id="cb8-11"><a href="#cb8-11" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> s[left]<span class="op">==</span>s[right]: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
-<span id="cb8-12"><a href="#cb8-12" aria-hidden="true" tabindex="-1"></a>        <span class="cf">else</span>: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
-<span id="cb8-13"><a href="#cb8-13" aria-hidden="true" tabindex="-1"></a>    s<span class="op">=</span><span class="st">''</span>.join(new)</span>
-<span id="cb8-14"><a href="#cb8-14" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(s)</span>
-<span id="cb8-15"><a href="#cb8-15" aria-hidden="true" tabindex="-1"></a>    i <span class="op">+=</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a>n <span class="op">=</span> <span class="dv">10</span></span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a>s <span class="op">=</span> <span class="st">'et cetera'</span></span>
+<span id="cb8-3"><a href="#cb8-3" tabindex="-1"></a><span class="bu">print</span>(s)</span>
+<span id="cb8-4"><a href="#cb8-4" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb8-5"><a href="#cb8-5" tabindex="-1"></a><span class="cf">while</span> i <span class="op">&lt;</span> n:</span>
+<span id="cb8-6"><a href="#cb8-6" tabindex="-1"></a>    <span class="co"># print('at', j)</span></span>
+<span id="cb8-7"><a href="#cb8-7" tabindex="-1"></a>    new <span class="op">=</span> <span class="st">''</span></span>
+<span id="cb8-8"><a href="#cb8-8" tabindex="-1"></a>    <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(<span class="bu">len</span>(s)):</span>
+<span id="cb8-9"><a href="#cb8-9" tabindex="-1"></a>        left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
+<span id="cb8-10"><a href="#cb8-10" tabindex="-1"></a>        right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>)<span class="op">%</span><span class="bu">len</span>(s)</span>
+<span id="cb8-11"><a href="#cb8-11" tabindex="-1"></a>        <span class="cf">if</span> s[left]<span class="op">==</span>s[right]: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
+<span id="cb8-12"><a href="#cb8-12" tabindex="-1"></a>        <span class="cf">else</span>: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
+<span id="cb8-13"><a href="#cb8-13" tabindex="-1"></a>    s<span class="op">=</span><span class="st">''</span>.join(new)</span>
+<span id="cb8-14"><a href="#cb8-14" tabindex="-1"></a>    <span class="bu">print</span>(s)</span>
+<span id="cb8-15"><a href="#cb8-15" tabindex="-1"></a>    i <span class="op">+=</span> <span class="dv">1</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -659,37 +658,37 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>Here’s one solution.</p>
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> string_machine(input_string, iterations):</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">"""</span></span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a><span class="co">    Takes input_string and generates a new string with -'s and *'s</span></span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="co">    corresponding to characters that have identical adjacent characters</span></span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a><span class="co">    or not, respectively.  Iterates through this procedure with the resultant</span></span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a><span class="co">    strings for the supplied number of iterations.</span></span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="co">    """</span></span>
-<span id="cb9-8"><a href="#cb9-8" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(input_string)</span>
-<span id="cb9-9"><a href="#cb9-9" aria-hidden="true" tabindex="-1"></a>    input_string_length <span class="op">=</span> <span class="bu">len</span>(input_string)</span>
-<span id="cb9-10"><a href="#cb9-10" aria-hidden="true" tabindex="-1"></a>    old <span class="op">=</span> input_string</span>
-<span id="cb9-11"><a href="#cb9-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(iterations):</span>
-<span id="cb9-12"><a href="#cb9-12" aria-hidden="true" tabindex="-1"></a>        new <span class="op">=</span> <span class="st">''</span></span>
-<span id="cb9-13"><a href="#cb9-13" aria-hidden="true" tabindex="-1"></a>        <span class="co"># iterate through characters in previous string</span></span>
-<span id="cb9-14"><a href="#cb9-14" aria-hidden="true" tabindex="-1"></a>        <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(input_string_length):</span>
-<span id="cb9-15"><a href="#cb9-15" aria-hidden="true" tabindex="-1"></a>            left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
-<span id="cb9-16"><a href="#cb9-16" aria-hidden="true" tabindex="-1"></a>            right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>) <span class="op">%</span> input_string_length  <span class="co"># ensure right index wraps around</span></span>
-<span id="cb9-17"><a href="#cb9-17" aria-hidden="true" tabindex="-1"></a>            <span class="cf">if</span> old[left] <span class="op">==</span> old[right]:</span>
-<span id="cb9-18"><a href="#cb9-18" aria-hidden="true" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
-<span id="cb9-19"><a href="#cb9-19" aria-hidden="true" tabindex="-1"></a>            <span class="cf">else</span>:</span>
-<span id="cb9-20"><a href="#cb9-20" aria-hidden="true" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
-<span id="cb9-21"><a href="#cb9-21" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(new)</span>
-<span id="cb9-22"><a href="#cb9-22" aria-hidden="true" tabindex="-1"></a>        <span class="co"># store new string as old</span></span>
-<span id="cb9-23"><a href="#cb9-23" aria-hidden="true" tabindex="-1"></a>        old <span class="op">=</span> new     </span>
-<span id="cb9-24"><a href="#cb9-24" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb9-25"><a href="#cb9-25" aria-hidden="true" tabindex="-1"></a>string_machine(<span class="st">'et cetera'</span>, <span class="dv">10</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="kw">def</span> string_machine(input_string, iterations):</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>    <span class="co">"""</span></span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a><span class="co">    Takes input_string and generates a new string with -'s and *'s</span></span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a><span class="co">    corresponding to characters that have identical adjacent characters</span></span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a><span class="co">    or not, respectively.  Iterates through this procedure with the resultant</span></span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a><span class="co">    strings for the supplied number of iterations.</span></span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a><span class="co">    """</span></span>
+<span id="cb9-8"><a href="#cb9-8" tabindex="-1"></a>    <span class="bu">print</span>(input_string)</span>
+<span id="cb9-9"><a href="#cb9-9" tabindex="-1"></a>    input_string_length <span class="op">=</span> <span class="bu">len</span>(input_string)</span>
+<span id="cb9-10"><a href="#cb9-10" tabindex="-1"></a>    old <span class="op">=</span> input_string</span>
+<span id="cb9-11"><a href="#cb9-11" tabindex="-1"></a>    <span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(iterations):</span>
+<span id="cb9-12"><a href="#cb9-12" tabindex="-1"></a>        new <span class="op">=</span> <span class="st">''</span></span>
+<span id="cb9-13"><a href="#cb9-13" tabindex="-1"></a>        <span class="co"># iterate through characters in previous string</span></span>
+<span id="cb9-14"><a href="#cb9-14" tabindex="-1"></a>        <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(input_string_length):</span>
+<span id="cb9-15"><a href="#cb9-15" tabindex="-1"></a>            left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
+<span id="cb9-16"><a href="#cb9-16" tabindex="-1"></a>            right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>) <span class="op">%</span> input_string_length  <span class="co"># ensure right index wraps around</span></span>
+<span id="cb9-17"><a href="#cb9-17" tabindex="-1"></a>            <span class="cf">if</span> old[left] <span class="op">==</span> old[right]:</span>
+<span id="cb9-18"><a href="#cb9-18" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
+<span id="cb9-19"><a href="#cb9-19" tabindex="-1"></a>            <span class="cf">else</span>:</span>
+<span id="cb9-20"><a href="#cb9-20" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
+<span id="cb9-21"><a href="#cb9-21" tabindex="-1"></a>        <span class="bu">print</span>(new)</span>
+<span id="cb9-22"><a href="#cb9-22" tabindex="-1"></a>        <span class="co"># store new string as old</span></span>
+<span id="cb9-23"><a href="#cb9-23" tabindex="-1"></a>        old <span class="op">=</span> new     </span>
+<span id="cb9-24"><a href="#cb9-24" tabindex="-1"></a></span>
+<span id="cb9-25"><a href="#cb9-25" tabindex="-1"></a>string_machine(<span class="st">'et cetera'</span>, <span class="dv">10</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -782,7 +781,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/18-style.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-07-29",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/19-wrap.html b/19-wrap.html
index 7a0afbf86..3fd5d02be 100644
--- a/19-wrap.html
+++ b/19-wrap.html
@@ -516,7 +516,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/19-wrap.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/20-feedback.html b/20-feedback.html
index 1b3fbf301..80e22bfbc 100644
--- a/20-feedback.html
+++ b/20-feedback.html
@@ -486,7 +486,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/20-feedback.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/404.html b/404.html
index 2d2911a1c..1322e80c4 100644
--- a/404.html
+++ b/404.html
@@ -464,8 +464,8 @@ <h1>Page not found</h1>
   "url": "https://swcarpentry.github.io/python-novice-gapminder/404.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/404.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/CODE_OF_CONDUCT.html b/CODE_OF_CONDUCT.html
index 50771ae60..6b04e15e4 100644
--- a/CODE_OF_CONDUCT.html
+++ b/CODE_OF_CONDUCT.html
@@ -454,7 +454,7 @@ <h1>Contributor Code of Conduct</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/CODE_OF_CONDUCT.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/LICENSE.html b/LICENSE.html
index 16dcbf0b5..df6fa8028 100644
--- a/LICENSE.html
+++ b/LICENSE.html
@@ -505,7 +505,7 @@ <h1>Licenses</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/LICENSE.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/aio.html b/aio.html
index 5d64d94e6..54c1083f7 100644
--- a/aio.html
+++ b/aio.html
@@ -559,12 +559,12 @@ <h3 class="card-title">Objectives</h3>
 <li>Type code into the browser and see the results after your JupyterLab
 server has finished executing your code</li>
 </ul>
-<div id="jupyterlab-what-about-jupyter-notebooks" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="jupyterlab-what-about-jupyter-notebooks" class="callout-inner">
-<h3 class="callout-title">JupyterLab? What about Jupyter notebooks?<a class="anchor" aria-label="anchor" href="#jupyterlab-what-about-jupyter-notebooks"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="jupyterlab-what-about-jupyter-notebooks">JupyterLab? What about Jupyter notebooks?<a class="anchor" aria-label="anchor" href="#jupyterlab-what-about-jupyter-notebooks"></a>
 </h3>
 <div class="callout-content">
 <p>JupyterLab is the <a href="https://jupyterlab.readthedocs.io/en/stable/getting_started/overview.html#overview" class="external-link">next
@@ -603,7 +603,7 @@ <h3 id="macos---command-line">macOS - Command Line<a class="anchor" aria-label="
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">BASH<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
+<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
 </div>
 </div>
 <div class="section level3">
@@ -617,7 +617,7 @@ <h3 id="windows-users---command-line">Windows Users - Command Line<a class="anch
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">BASH<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
+<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
 </div>
 </div>
 <div class="section level3">
@@ -691,12 +691,12 @@ <h3 id="menu-bar">Menu Bar<a class="anchor" aria-label="anchor" href="#menu-bar"
 <strong>Help:</strong> A list of JupyterLab and kernel help
 links.</li>
 </ul>
-<div id="kernels" class="callout callout">
+<div id="callout2" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="kernels" class="callout-inner">
-<h3 class="callout-title">Kernels<a class="anchor" aria-label="anchor" href="#kernels"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="kernels">Kernels<a class="anchor" aria-label="anchor" href="#kernels"></a>
 </h3>
 <div class="callout-content">
 <p>The JupyterLab <a href="https://jupyterlab.readthedocs.io/en/stable/user/documents_kernels.html" class="external-link">docs</a>
@@ -786,12 +786,12 @@ <h3 id="main-work-area">Main Work Area<a class="anchor" aria-label="anchor" href
 notebook documentation</a>.</p>
 <p align="center">
 <img alt="Example Jupyter Notebook" src="fig/0_jupyterlab_notebook_screenshot.png" width="750" class="figure"></p>
-<div id="how-its-stored" class="callout callout">
+<div id="callout3" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="how-its-stored" class="callout-inner">
-<h3 class="callout-title">How It’s Stored<a class="anchor" aria-label="anchor" href="#how-its-stored"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="how-its-stored">How It’s Stored<a class="anchor" aria-label="anchor" href="#how-its-stored"></a>
 </h3>
 <div class="callout-content">
 <ul>
@@ -841,12 +841,12 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </div>
 </div>
 </div>
-<div id="code-vs.-text" class="callout callout">
+<div id="callout4" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="code-vs.-text" class="callout-inner">
-<h3 class="callout-title">Code vs. Text<a class="anchor" aria-label="anchor" href="#code-vs.-text"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="code-vs--text">Code vs. Text<a class="anchor" aria-label="anchor" href="#code-vs--text"></a>
 </h3>
 <div class="callout-content">
 <p>Jupyter mixes code and text in different types of blocks, called
@@ -1120,8 +1120,8 @@ <h3 class="callout-title">More Math<a class="anchor" aria-label="anchor" href="#
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="dv">7</span> <span class="op">*</span> <span class="dv">3</span></span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="dv">2</span> <span class="op">+</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="dv">7</span> <span class="op">*</span> <span class="dv">3</span></span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="dv">2</span> <span class="op">+</span> <span class="dv">1</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -1137,7 +1137,7 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="dv">3</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="dv">3</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -1158,8 +1158,8 @@ <h3 class="callout-title">Change an Existing Cell from Code to
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span></span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(x)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span></span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a><span class="bu">print</span>(x)</span></code></pre>
 </div>
 <p>And then run it with <kbd>Shift</kbd>+<kbd>Return</kbd> to be sure
 that it works as a code cell. Now go back to the cell and use
@@ -1183,7 +1183,7 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span> <span class="bu">print</span>(x)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span> <span class="bu">print</span>(x)</span></code></pre>
 </div>
 </div>
 </div>
@@ -1340,8 +1340,8 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">42</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>first_name <span class="op">=</span> <span class="st">'Ahmed'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">42</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>first_name <span class="op">=</span> <span class="st">'Ahmed'</span></span></code></pre>
 </div>
 </li>
 </ul></section><section id="use-print-to-display-values."><h2 class="section-heading">Use <code>print</code> to display values.<a class="anchor" aria-label="anchor" href="#use-print-to-display-values."></a>
@@ -1363,7 +1363,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(first_name, <span class="st">'is'</span>, age, <span class="st">'years old'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(first_name, <span class="st">'is'</span>, age, <span class="st">'years old'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1386,7 +1386,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(last_name)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="bu">print</span>(last_name)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1403,12 +1403,12 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 informative.</li>
 <li>We will look at error messages in detail <a href="17-scope.html#reading-error-messages">later</a>.</li>
 </ul>
-<div id="variables-persist-between-cells" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="variables-persist-between-cells" class="callout-inner">
-<h3 class="callout-title">Variables Persist Between Cells<a class="anchor" aria-label="anchor" href="#variables-persist-between-cells"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="variables-persist-between-cells">Variables Persist Between Cells<a class="anchor" aria-label="anchor" href="#variables-persist-between-cells"></a>
 </h3>
 <div class="callout-content">
 <p>Be aware that it is the <em>order</em> of execution of cells that is
@@ -1422,12 +1422,12 @@ <h3 class="callout-title">Variables Persist Between Cells<a class="anchor" aria-
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(myval)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a><span class="bu">print</span>(myval)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>myval <span class="op">=</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>myval <span class="op">=</span> <span class="dv">1</span></span></code></pre>
 </div>
 <p>If you execute this in order, the first cell will give an error.
 However, if you run the first cell <em>after</em> the second cell it
@@ -1452,8 +1452,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> age <span class="op">+</span> <span class="dv">3</span></span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Age in three years:'</span>, age)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a>age <span class="op">=</span> age <span class="op">+</span> <span class="dv">3</span></span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Age in three years:'</span>, age)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1475,13 +1475,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <li>Use the position’s index in square brackets to get the character at
 that position.</li>
 </ul>
-<figure><img src="fig/2_indexing.svg" alt="" class="figure mx-auto d-block"><figcaption>A line of Python code, print(atom_name[0]),
+<figure><img src="fig/2_indexing.svg" alt="A line of Python code, print(atom_name[0]), demonstrates that using the zero index will output just the initial letter, in this case ‘h’ for helium." class="figure mx-auto d-block"><div class="figcaption">A line of Python code, print(atom_name[0]),
 demonstrates that using the zero index will output just the initial
-letter, in this case ‘h’ for helium.</figcaption></figure><div class="codewrapper sourceCode" id="cb10">
+letter, in this case ‘h’ for helium.</div>
+</figure><div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'helium'</span></span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'helium'</span></span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1512,8 +1513,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'sodium'</span></span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>:<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'sodium'</span></span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>:<span class="dv">3</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1527,7 +1528,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="st">'helium'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="st">'helium'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1555,9 +1556,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>flabadab <span class="op">=</span> <span class="dv">42</span></span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a>ewr_422_yY <span class="op">=</span> <span class="st">'Ahmed'</span></span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(ewr_422_yY, <span class="st">'is'</span>, flabadab, <span class="st">'years old'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>flabadab <span class="op">=</span> <span class="dv">42</span></span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a>ewr_422_yY <span class="op">=</span> <span class="st">'Ahmed'</span></span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a><span class="bu">print</span>(ewr_422_yY, <span class="st">'is'</span>, flabadab, <span class="st">'years old'</span>)</span></code></pre>
 </div>
 <ul>
 <li>Use meaningful variable names to help other people understand what
@@ -1577,12 +1578,12 @@ <h3 class="callout-title">Swapping Values<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Command  # Value of x   # Value of y   # Value of swap #</span></span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> <span class="fl">1.0</span>    <span class="co">#              #              #               #</span></span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a>y <span class="op">=</span> <span class="fl">3.0</span>    <span class="co">#              #              #               #</span></span>
-<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a>swap <span class="op">=</span> x   <span class="co">#              #              #               #</span></span>
-<span id="cb17-5"><a href="#cb17-5" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> y      <span class="co">#              #              #               #</span></span>
-<span id="cb17-6"><a href="#cb17-6" aria-hidden="true" tabindex="-1"></a>y <span class="op">=</span> swap   <span class="co">#              #              #               #</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="co"># Command  # Value of x   # Value of y   # Value of swap #</span></span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>x <span class="op">=</span> <span class="fl">1.0</span>    <span class="co">#              #              #               #</span></span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a>y <span class="op">=</span> <span class="fl">3.0</span>    <span class="co">#              #              #               #</span></span>
+<span id="cb17-4"><a href="#cb17-4" tabindex="-1"></a>swap <span class="op">=</span> x   <span class="co">#              #              #               #</span></span>
+<span id="cb17-5"><a href="#cb17-5" tabindex="-1"></a>x <span class="op">=</span> y      <span class="co">#              #              #               #</span></span>
+<span id="cb17-6"><a href="#cb17-6" tabindex="-1"></a>y <span class="op">=</span> swap   <span class="co">#              #              #               #</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -1592,7 +1593,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1625,9 +1626,9 @@ <h3 class="callout-title">Predicting Values<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'left'</span></span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>position <span class="op">=</span> initial</span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'right'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'left'</span></span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>position <span class="op">=</span> initial</span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'right'</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -1637,12 +1638,12 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(position)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a><span class="bu">print</span>(position)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1677,7 +1678,7 @@ <h3 class="callout-title">Challenge<a class="anchor" aria-label="anchor" href="#
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Numbers are not strings or sequences and Python will raise an error
 if you try to perform an index operation on a number. In the <a href="03-types-conversion.html">next lesson on types and type
@@ -1688,8 +1689,8 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">=</span> <span class="dv">123</span></span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>a <span class="op">=</span> <span class="dv">123</span></span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1699,8 +1700,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">=</span> <span class="bu">str</span>(<span class="dv">123</span>)</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a>a <span class="op">=</span> <span class="bu">str</span>(<span class="dv">123</span>)</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1735,7 +1736,7 @@ <h3 class="callout-title">Choosing a Name<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p><code>minutes</code> is better because <code>min</code> might mean
 something like “minimum” (and actually is an existing built-in function
@@ -1756,8 +1757,8 @@ <h3 class="callout-title">Slicing practice<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'carbon'</span></span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'atom_name[1:3] is:'</span>, atom_name[<span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'carbon'</span></span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'atom_name[1:3] is:'</span>, atom_name[<span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -1767,7 +1768,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1790,7 +1791,7 @@ <h3 class="callout-title">Slicing concepts<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>species_name <span class="op">=</span> <span class="st">"Acacia buxifolia"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>species_name <span class="op">=</span> <span class="st">"Acacia buxifolia"</span></span></code></pre>
 </div>
 <p>What would these expressions return?</p>
 <ol style="list-style-type: decimal">
@@ -1817,7 +1818,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solutions</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <ol style="list-style-type: decimal">
 <li>
@@ -1947,7 +1948,7 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="dv">52</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="dv">52</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1957,8 +1958,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>fitness <span class="op">=</span> <span class="st">'average'</span></span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(fitness))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a>fitness <span class="op">=</span> <span class="st">'average'</span></span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(fitness))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1975,7 +1976,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span> <span class="op">-</span> <span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span> <span class="op">-</span> <span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1985,7 +1986,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'hello'</span> <span class="op">-</span> <span class="st">'h'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'hello'</span> <span class="op">-</span> <span class="st">'h'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2006,8 +2007,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>full_name <span class="op">=</span> <span class="st">'Ahmed'</span> <span class="op">+</span> <span class="st">' '</span> <span class="op">+</span> <span class="st">'Walsh'</span></span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(full_name)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>full_name <span class="op">=</span> <span class="st">'Ahmed'</span> <span class="op">+</span> <span class="st">' '</span> <span class="op">+</span> <span class="st">'Walsh'</span></span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="bu">print</span>(full_name)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2026,8 +2027,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>separator <span class="op">=</span> <span class="st">'='</span> <span class="op">*</span> <span class="dv">10</span></span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(separator)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>separator <span class="op">=</span> <span class="st">'='</span> <span class="op">*</span> <span class="dv">10</span></span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="bu">print</span>(separator)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2044,7 +2045,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(full_name))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(full_name))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2057,7 +2058,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="dv">52</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="dv">52</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2079,7 +2080,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2100,8 +2101,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="bu">int</span>(<span class="st">'2'</span>))</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">str</span>(<span class="dv">1</span>) <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="bu">int</span>(<span class="st">'2'</span>))</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">str</span>(<span class="dv">1</span>) <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2122,8 +2123,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'half is'</span>, <span class="dv">1</span> <span class="op">/</span> <span class="fl">2.0</span>)</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'three squared is'</span>, <span class="fl">3.0</span> <span class="op">**</span> <span class="dv">2</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'half is'</span>, <span class="dv">1</span> <span class="op">/</span> <span class="fl">2.0</span>)</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'three squared is'</span>, <span class="fl">3.0</span> <span class="op">**</span> <span class="dv">2</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2142,10 +2143,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">1</span></span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a>variable_two <span class="op">=</span> <span class="dv">5</span> <span class="op">*</span> variable_one</span>
-<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">2</span></span>
-<span id="cb23-4"><a href="#cb23-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first is'</span>, variable_one, <span class="st">'and second is'</span>, variable_two)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">1</span></span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a>variable_two <span class="op">=</span> <span class="dv">5</span> <span class="op">*</span> variable_one</span>
+<span id="cb23-3"><a href="#cb23-3" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">2</span></span>
+<span id="cb23-4"><a href="#cb23-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first is'</span>, variable_one, <span class="st">'and second is'</span>, variable_two)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2178,7 +2179,7 @@ <h3 class="callout-title">Fractions<a class="anchor" aria-label="anchor" href="#
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>It is a floating-point number (often abbreviated “float”). It is
 possible to find out by using the built-in function
@@ -2186,7 +2187,7 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="fl">3.4</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="fl">3.4</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2214,15 +2215,15 @@ <h3 class="callout-title">Automatic Type Conversion<a class="anchor" aria-label=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>It is a float: integers are automatically converted to floats as
 necessary.</p>
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="fl">3.25</span> <span class="op">+</span> <span class="dv">4</span></span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result, <span class="st">'is'</span>, <span class="bu">type</span>(result))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>result <span class="op">=</span> <span class="fl">3.25</span> <span class="op">+</span> <span class="dv">4</span></span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a><span class="bu">print</span>(result, <span class="st">'is'</span>, <span class="bu">type</span>(result))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2262,7 +2263,7 @@ <h3 class="callout-title">Choose a Type<a class="anchor" aria-label="anchor" hre
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>The answers to the questions are:</p>
 <ol style="list-style-type: decimal">
@@ -2297,9 +2298,9 @@ <h3 class="callout-title">Division Types<a class="anchor" aria-label="anchor" hr
 <div class="codewrapper sourceCode" id="cb29">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 // 3:'</span>, <span class="dv">5</span> <span class="op">//</span> <span class="dv">3</span>)</span>
-<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 / 3:'</span>, <span class="dv">5</span> <span class="op">/</span> <span class="dv">3</span>)</span>
-<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 % 3:'</span>, <span class="dv">5</span> <span class="op">%</span> <span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 // 3:'</span>, <span class="dv">5</span> <span class="op">//</span> <span class="dv">3</span>)</span>
+<span id="cb29-2"><a href="#cb29-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 / 3:'</span>, <span class="dv">5</span> <span class="op">/</span> <span class="dv">3</span>)</span>
+<span id="cb29-3"><a href="#cb29-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 % 3:'</span>, <span class="dv">5</span> <span class="op">%</span> <span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2320,7 +2321,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>We want the minimum number of surveys that reaches everyone once,
 which is the rounded up value of
@@ -2332,11 +2333,11 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>num_subjects <span class="op">=</span> <span class="dv">600</span></span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a>num_per_survey <span class="op">=</span> <span class="dv">42</span></span>
-<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a>num_surveys <span class="op">=</span> (num_subjects <span class="op">-</span> <span class="dv">1</span>) <span class="op">//</span> num_per_survey <span class="op">+</span> <span class="dv">1</span></span>
-<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb31-5"><a href="#cb31-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(num_subjects, <span class="st">'subjects,'</span>, num_per_survey, <span class="st">'per survey:'</span>, num_surveys)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>num_subjects <span class="op">=</span> <span class="dv">600</span></span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a>num_per_survey <span class="op">=</span> <span class="dv">42</span></span>
+<span id="cb31-3"><a href="#cb31-3" tabindex="-1"></a>num_surveys <span class="op">=</span> (num_subjects <span class="op">-</span> <span class="dv">1</span>) <span class="op">//</span> num_per_survey <span class="op">+</span> <span class="dv">1</span></span>
+<span id="cb31-4"><a href="#cb31-4" tabindex="-1"></a></span>
+<span id="cb31-5"><a href="#cb31-5" tabindex="-1"></a><span class="bu">print</span>(num_subjects, <span class="st">'subjects,'</span>, num_per_survey, <span class="st">'per survey:'</span>, num_surveys)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2361,8 +2362,8 @@ <h3 class="callout-title">Strings to Numbers<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb33">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"3.4"</span>))</span>
-<span id="cb33-2"><a href="#cb33-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"float to int:"</span>, <span class="bu">int</span>(<span class="fl">3.4</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"3.4"</span>))</span>
+<span id="cb33-2"><a href="#cb33-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"float to int:"</span>, <span class="bu">int</span>(<span class="fl">3.4</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2375,7 +2376,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"Hello world!"</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"Hello world!"</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2394,7 +2395,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"fractional string to int:"</span>, <span class="bu">int</span>(<span class="st">"3.4"</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"fractional string to int:"</span>, <span class="bu">int</span>(<span class="st">"3.4"</span>))</span></code></pre>
 </div>
 </div>
 </div>
@@ -2404,7 +2405,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>What do you expect this program to do? It would not be so
 unreasonable to expect the Python 3 <code>int</code> command to convert
@@ -2414,7 +2415,7 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb38">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a><span class="bu">int</span>(<span class="st">"3.4"</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" tabindex="-1"></a><span class="bu">int</span>(<span class="st">"3.4"</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2431,7 +2432,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb40">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a><span class="bu">int</span>(<span class="bu">float</span>(<span class="st">"3.4"</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" tabindex="-1"></a><span class="bu">int</span>(<span class="bu">float</span>(<span class="st">"3.4"</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2455,9 +2456,9 @@ <h3 class="callout-title">Arithmetic with Different Types<a class="anchor" aria-
 <div class="codewrapper sourceCode" id="cb42">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" aria-hidden="true" tabindex="-1"></a>first <span class="op">=</span> <span class="fl">1.0</span></span>
-<span id="cb42-2"><a href="#cb42-2" aria-hidden="true" tabindex="-1"></a>second <span class="op">=</span> <span class="st">"1"</span></span>
-<span id="cb42-3"><a href="#cb42-3" aria-hidden="true" tabindex="-1"></a>third <span class="op">=</span> <span class="st">"1.1"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" tabindex="-1"></a>first <span class="op">=</span> <span class="fl">1.0</span></span>
+<span id="cb42-2"><a href="#cb42-2" tabindex="-1"></a>second <span class="op">=</span> <span class="st">"1"</span></span>
+<span id="cb42-3"><a href="#cb42-3" tabindex="-1"></a>third <span class="op">=</span> <span class="st">"1.1"</span></span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li><code>first + float(second)</code></li>
@@ -2475,7 +2476,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Show me the solution</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <p>Answer: 1 and 4</p>
 </div>
@@ -2497,9 +2498,9 @@ <h3 class="callout-title">Complex Numbers<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb43">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a>a_complex_number <span class="op">=</span> <span class="dv">6</span> <span class="op">+</span> <span class="ot">2j</span></span>
-<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.real)</span>
-<span id="cb43-3"><a href="#cb43-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.imag)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" tabindex="-1"></a>a_complex_number <span class="op">=</span> <span class="dv">6</span> <span class="op">+</span> <span class="ot">2j</span></span>
+<span id="cb43-2"><a href="#cb43-2" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.real)</span>
+<span id="cb43-3"><a href="#cb43-3" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.imag)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2522,7 +2523,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
 <div class="accordion-body">
 <ol style="list-style-type: decimal">
 <li>Standard mathematics treatments typically use <code>i</code> to
@@ -2611,8 +2612,8 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="co"># This sentence isn't executed by Python.</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>adjustment <span class="op">=</span> <span class="fl">0.5</span>   <span class="co"># Neither is this - anything after '#' is ignored.</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="co"># This sentence isn't executed by Python.</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>adjustment <span class="op">=</span> <span class="fl">0.5</span>   <span class="co"># Neither is this - anything after '#' is ignored.</span></span></code></pre>
 </div>
 </section><section id="a-function-may-take-zero-or-more-arguments."><h2 class="section-heading">A function may take zero or more arguments.<a class="anchor" aria-label="anchor" href="#a-function-may-take-zero-or-more-arguments."></a>
 </h2>
@@ -2639,9 +2640,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'before'</span>)</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>()</span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'after'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'before'</span>)</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a><span class="bu">print</span>()</span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'after'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2662,8 +2663,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">print</span>(<span class="st">'example'</span>)</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of print is'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">print</span>(<span class="st">'example'</span>)</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of print is'</span>, result)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2688,8 +2689,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>))</span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">min</span>(<span class="st">'a'</span>, <span class="st">'A'</span>, <span class="st">'0'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>))</span>
+<span id="cb6-2"><a href="#cb6-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">min</span>(<span class="st">'a'</span>, <span class="st">'A'</span>, <span class="st">'0'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2715,7 +2716,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="st">'a'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="st">'a'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2737,7 +2738,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2750,7 +2751,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>, <span class="dv">1</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>, <span class="dv">1</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2771,13 +2772,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>  <span class="co"># creation of a string object </span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(my_string))       <span class="co"># the len function takes a string as an argument and returns the length of the string</span></span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.swapcase()) <span class="co"># calling the swapcase method on the my_string object</span></span>
-<span id="cb14-6"><a href="#cb14-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb14-7"><a href="#cb14-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.<span class="fu">__len__</span>())  <span class="co"># calling the internal __len__ method on the my_string object, used by len(my_string)</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>  <span class="co"># creation of a string object </span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a></span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(my_string))       <span class="co"># the len function takes a string as an argument and returns the length of the string</span></span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a></span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a><span class="bu">print</span>(my_string.swapcase()) <span class="co"># calling the swapcase method on the my_string object</span></span>
+<span id="cb14-6"><a href="#cb14-6" tabindex="-1"></a></span>
+<span id="cb14-7"><a href="#cb14-7" tabindex="-1"></a><span class="bu">print</span>(my_string.<span class="fu">__len__</span>())  <span class="co"># calling the internal __len__ method on the my_string object, used by len(my_string)</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2793,10 +2794,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.isupper())          <span class="co"># Not all the letters are uppercase</span></span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.upper())            <span class="co"># This capitalizes all the letters</span></span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.upper().isupper())  <span class="co"># Now all the letters are uppercase</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a><span class="bu">print</span>(my_string.isupper())          <span class="co"># Not all the letters are uppercase</span></span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a><span class="bu">print</span>(my_string.upper())            <span class="co"># This capitalizes all the letters</span></span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a></span>
+<span id="cb16-4"><a href="#cb16-4" tabindex="-1"></a><span class="bu">print</span>(my_string.upper().isupper())  <span class="co"># Now all the letters are uppercase</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2815,7 +2816,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(<span class="bu">round</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a><span class="bu">help</span>(<span class="bu">round</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2851,8 +2852,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Forgot to close the quote marks around the string.</span></span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>name <span class="op">=</span> <span class="st">'Feng</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a><span class="co"># Forgot to close the quote marks around the string.</span></span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>name <span class="op">=</span> <span class="st">'Feng</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2865,8 +2866,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a><span class="co"># An extra '=' in the assignment.</span></span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> <span class="op">=</span> <span class="dv">52</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a><span class="co"># An extra '=' in the assignment.</span></span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>age <span class="op">=</span> <span class="op">=</span> <span class="dv">52</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2882,7 +2883,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"hello world"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"hello world"</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2912,8 +2913,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">53</span></span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a>remaining <span class="op">=</span> <span class="dv">100</span> <span class="op">-</span> aege <span class="co"># mis-spelled 'age'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">53</span></span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a>remaining <span class="op">=</span> <span class="dv">100</span> <span class="op">-</span> aege <span class="co"># mis-spelled 'age'</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2946,8 +2947,8 @@ <h3 class="callout-title">What Happens When<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>radiance <span class="op">=</span> <span class="fl">1.0</span></span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a>radiance <span class="op">=</span> <span class="bu">max</span>(<span class="fl">2.1</span>, <span class="fl">2.0</span> <span class="op">+</span> <span class="bu">min</span>(radiance, <span class="fl">1.1</span> <span class="op">*</span> radiance <span class="op">-</span> <span class="fl">0.5</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>radiance <span class="op">=</span> <span class="fl">1.0</span></span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a>radiance <span class="op">=</span> <span class="bu">max</span>(<span class="fl">2.1</span>, <span class="fl">2.0</span> <span class="op">+</span> <span class="bu">min</span>(radiance, <span class="fl">1.1</span> <span class="op">*</span> radiance <span class="op">-</span> <span class="fl">0.5</span>))</span></code></pre>
 </div>
 </div>
 </div>
@@ -2990,12 +2991,12 @@ <h3 class="callout-title">Spot the Difference<a class="anchor" aria-label="ancho
 <div class="codewrapper sourceCode" id="cb29">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a>easy_string <span class="op">=</span> <span class="st">"abc"</span></span>
-<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span>
-<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a>rich <span class="op">=</span> <span class="st">"gold"</span></span>
-<span id="cb29-4"><a href="#cb29-4" aria-hidden="true" tabindex="-1"></a>poor <span class="op">=</span> <span class="st">"tin"</span></span>
-<span id="cb29-5"><a href="#cb29-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span>
-<span id="cb29-6"><a href="#cb29-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" tabindex="-1"></a>easy_string <span class="op">=</span> <span class="st">"abc"</span></span>
+<span id="cb29-2"><a href="#cb29-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span>
+<span id="cb29-3"><a href="#cb29-3" tabindex="-1"></a>rich <span class="op">=</span> <span class="st">"gold"</span></span>
+<span id="cb29-4"><a href="#cb29-4" tabindex="-1"></a>poor <span class="op">=</span> <span class="st">"tin"</span></span>
+<span id="cb29-5"><a href="#cb29-5" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span>
+<span id="cb29-6"><a href="#cb29-6" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
 </div>
 </div>
 </div>
@@ -3010,7 +3011,7 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3020,7 +3021,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3030,7 +3031,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3109,12 +3110,12 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </div>
 </div>
 </div>
-<div id="explore-the-python-docs" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="explore-the-python-docs" class="callout-inner">
-<h3 class="callout-title">Explore the Python docs!<a class="anchor" aria-label="anchor" href="#explore-the-python-docs"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="explore-the-python-docs">Explore the Python docs!<a class="anchor" aria-label="anchor" href="#explore-the-python-docs"></a>
 </h3>
 <div class="callout-content">
 <p>The <a href="https://docs.python.org/3/" class="external-link">official Python
@@ -3236,12 +3237,12 @@ <h3 class="card-title">Objectives</h3>
 Index).</li>
 <li>We will see later how to write new libraries.</li>
 </ul>
-<div id="libraries-and-modules" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="libraries-and-modules" class="callout-inner">
-<h3 class="callout-title">Libraries and modules<a class="anchor" aria-label="anchor" href="#libraries-and-modules"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="libraries-and-modules">Libraries and modules<a class="anchor" aria-label="anchor" href="#libraries-and-modules"></a>
 </h3>
 <div class="callout-content">
 <p>A library is a collection of modules, but the terms are often used
@@ -3268,10 +3269,10 @@ <h3 class="callout-title">Libraries and modules<a class="anchor" aria-label="anc
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pi is'</span>, math.pi)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, math.cos(math.pi))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> math</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pi is'</span>, math.pi)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, math.cos(math.pi))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3298,7 +3299,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(math)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="bu">help</span>(math)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3338,9 +3339,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> cos, pi</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, cos(pi))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> cos, pi</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a></span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, cos(pi))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3359,9 +3360,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, m.cos(m.pi))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a></span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, m.cos(m.pi))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3432,7 +3433,7 @@ <h3 class="callout-title">Locating the Right Module<a class="anchor" aria-label=
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">'ACTTGCTTGAC'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">'ACTTGCTTGAC'</span></span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>Which <a href="https://docs.python.org/3/library/" class="external-link">standard
@@ -3461,18 +3462,18 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>random_index <span class="op">=</span> randrange(<span class="bu">len</span>(bases))</span>
-<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(bases[random_index])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a></span>
+<span id="cb10-3"><a href="#cb10-3" tabindex="-1"></a>random_index <span class="op">=</span> randrange(<span class="bu">len</span>(bases))</span>
+<span id="cb10-4"><a href="#cb10-4" tabindex="-1"></a><span class="bu">print</span>(bases[random_index])</span></code></pre>
 </div>
 <p>or more compactly:</p>
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(bases[randrange(<span class="bu">len</span>(bases))])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a></span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a><span class="bu">print</span>(bases[randrange(<span class="bu">len</span>(bases))])</span></code></pre>
 </div>
 <p>Perhaps you found the <a href="https://docs.python.org/3/library/random.html#random.sample" class="external-link"><code>random.sample</code></a>
 function? It allows for slightly less typing but might be a bit harder
@@ -3480,9 +3481,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> sample</span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(sample(bases, <span class="dv">1</span>)[<span class="dv">0</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> sample</span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a></span>
+<span id="cb12-3"><a href="#cb12-3" tabindex="-1"></a><span class="bu">print</span>(sample(bases, <span class="dv">1</span>)[<span class="dv">0</span>])</span></code></pre>
 </div>
 <p>Note that this function returns a list of values. We will learn about
 lists in <a href="11-lists.html">episode 11</a>.</p>
@@ -3491,9 +3492,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> choice</span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(choice(bases))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> choice</span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a></span>
+<span id="cb13-3"><a href="#cb13-3" tabindex="-1"></a><span class="bu">print</span>(choice(bases))</span></code></pre>
 </div>
 </div>
 </div>
@@ -3514,12 +3515,12 @@ <h3 class="callout-title">Jigsaw Puzzle (Parson’s Problem) Programming
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>bases<span class="op">=</span><span class="st">"ACTTGCTTGAC"</span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math</span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a>___ <span class="op">=</span> random.randrange(n_bases)</span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a>___ <span class="op">=</span> <span class="bu">len</span>(bases)</span>
-<span id="cb14-6"><a href="#cb14-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base "</span>, bases[___], <span class="st">"base index"</span>, ___)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>bases<span class="op">=</span><span class="st">"ACTTGCTTGAC"</span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a><span class="im">import</span> math</span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a>___ <span class="op">=</span> random.randrange(n_bases)</span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a>___ <span class="op">=</span> <span class="bu">len</span>(bases)</span>
+<span id="cb14-6"><a href="#cb14-6" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base "</span>, bases[___], <span class="st">"base index"</span>, ___)</span></code></pre>
 </div>
 </div>
 </div>
@@ -3534,12 +3535,12 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math </span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">"ACTTGCTTGAC"</span> </span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a>n_bases <span class="op">=</span> <span class="bu">len</span>(bases)</span>
-<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a>idx <span class="op">=</span> random.randrange(n_bases)</span>
-<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base"</span>, bases[idx], <span class="st">"base index"</span>, idx)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="im">import</span> math </span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">"ACTTGCTTGAC"</span> </span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a>n_bases <span class="op">=</span> <span class="bu">len</span>(bases)</span>
+<span id="cb15-5"><a href="#cb15-5" tabindex="-1"></a>idx <span class="op">=</span> random.randrange(n_bases)</span>
+<span id="cb15-6"><a href="#cb15-6" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base"</span>, bases[idx], <span class="st">"base index"</span>, idx)</span></code></pre>
 </div>
 </div>
 </div>
@@ -3594,9 +3595,9 @@ <h3 class="callout-title">Importing With Aliases<a class="anchor" aria-label="an
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> ____.degrees(____.pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(____)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>angle <span class="op">=</span> ____.degrees(____.pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a><span class="bu">print</span>(____)</span></code></pre>
 </div>
 </div>
 </div>
@@ -3611,17 +3612,17 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
-<span id="cb18-2"><a href="#cb18-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> m.degrees(m.pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb18-3"><a href="#cb18-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
+<span id="cb18-2"><a href="#cb18-2" tabindex="-1"></a>angle <span class="op">=</span> m.degrees(m.pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb18-3"><a href="#cb18-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 <p>can be written as</p>
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> math.degrees(math.pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="im">import</span> math</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>angle <span class="op">=</span> math.degrees(math.pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 <p>Since you just wrote the code and are familiar with it, you might
 actually find the first version easier to read. But when trying to read
@@ -3712,9 +3713,9 @@ <h3 class="callout-title">Importing Specific Items<a class="anchor" aria-label="
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>____ math <span class="im">import</span> ____, ____</span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>____ math <span class="im">import</span> ____, ____</span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 </div>
 </div>
@@ -3729,9 +3730,9 @@ <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> degrees, pi</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> degrees, pi</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 <p>Most likely you find this version easier to read since it’s less
 dense. The main reason not to use this form of import is to avoid name
@@ -3760,8 +3761,8 @@ <h3 class="callout-title">Reading Error Messages<a class="anchor" aria-label="an
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> log</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>log(<span class="dv">0</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> log</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>log(<span class="dv">0</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -3878,10 +3879,10 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>data_oceania <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>data_oceania <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a><span class="bu">print</span>(data_oceania)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3911,12 +3912,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 multiple dataframes so we won’t accidentally overwrite a dataframe or
 read from the wrong one.</li>
 </ul>
-<div id="file-not-found" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="file-not-found" class="callout-inner">
-<h3 class="callout-title">File Not Found<a class="anchor" aria-label="anchor" href="#file-not-found"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="file-not-found">File Not Found<a class="anchor" aria-label="anchor" href="#file-not-found"></a>
 </h3>
 <div class="callout-content">
 <p>Our lessons store their data files in a <code>data</code>
@@ -3949,8 +3950,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>data_oceania_country <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a>data_oceania_country <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3977,7 +3978,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>data_oceania_country.info()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a>data_oceania_country.info()</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4031,7 +4032,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.columns)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.columns)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4053,7 +4054,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.T)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.T)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4082,7 +4083,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.describe())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.describe())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4141,7 +4142,7 @@ <h3 class="callout-title">Reading Other Data<a class="anchor" aria-label="anchor
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>To read in a CSV, we use <code>pd.read_csv</code> and pass the
 filename <code>'data/gapminder_gdp_americas.csv'</code> to it. We also
@@ -4152,8 +4153,8 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>data_americas <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_americas.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a>data_americas.describe()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>data_americas <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_americas.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a>data_americas.describe()</span></code></pre>
 </div>
 </div>
 </div>
@@ -4185,7 +4186,7 @@ <h3 class="callout-title">Inspecting Data<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <ol style="list-style-type: decimal">
 <li>We can check out the first five rows of <code>data_americas</code>
@@ -4198,7 +4199,7 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>data_americas.head(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a>data_americas.head(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4238,14 +4239,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>americas_flipped <span class="op">=</span> data_americas.T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>americas_flipped <span class="op">=</span> data_americas.T</span></code></pre>
 </div>
 <p>We can then view the last three columns of <code>americas</code> by
 viewing the last three rows of <code>americas_flipped</code>:</p>
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4275,14 +4276,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>).T    </span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>).T    </span></code></pre>
 </div>
 <p><strong>Note:</strong> we could have done the above in a single line
 of code by ‘chaining’ the commands:</p>
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a>data_americas.T.tail(n<span class="op">=</span><span class="dv">3</span>).T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a>data_americas.T.tail(n<span class="op">=</span><span class="dv">3</span>).T</span></code></pre>
 </div>
 </div>
 </div>
@@ -4320,7 +4321,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>We need to specify the path to the file of interest in the call to
 <code>pd.read_csv</code>. We first need to ‘jump’ out of the folder
@@ -4330,7 +4331,7 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a>data_microbes <span class="op">=</span> pd.read_csv(<span class="st">'../field_data/microbes.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a>data_microbes <span class="op">=</span> pd.read_csv(<span class="st">'../field_data/microbes.csv'</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -4358,22 +4359,22 @@ <h3 class="callout-title">Writing Data<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>In order to write the DataFrame <code>data_americas</code> to a file
 called <code>processed.csv</code>, execute the following command:</p>
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a>data_americas.to_csv(<span class="st">'processed.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a>data_americas.to_csv(<span class="st">'processed.csv'</span>)</span></code></pre>
 </div>
 <p>For help on <code>read_csv</code> or <code>to_csv</code>, you could
 execute, for example:</p>
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(data_americas.to_csv)</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(pd.read_csv)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="bu">help</span>(data_americas.to_csv)</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a><span class="bu">help</span>(pd.read_csv)</span></code></pre>
 </div>
 <p>Note that <code>help(to_csv)</code> or <code>help(pd.to_csv)</code>
 throws an error! This is due to the fact that <code>to_csv</code> is not
@@ -4479,9 +4480,9 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.iloc[<span class="dv">0</span>, <span class="dv">0</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="bu">print</span>(data.iloc[<span class="dv">0</span>, <span class="dv">0</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4498,7 +4499,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4514,7 +4515,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, :])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, :])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4540,7 +4541,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[:, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[:, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4569,7 +4570,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4598,7 +4599,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">max</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">max</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4611,7 +4612,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">min</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">min</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4632,12 +4633,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Use a subset of data to keep output readable.</span></span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>subset <span class="op">=</span> data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>]</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Subset of data:</span><span class="ch">\n</span><span class="st">'</span>, subset)</span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Which values were greater than 10000 ?</span></span>
-<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'</span><span class="ch">\n</span><span class="st">Where are values large?</span><span class="ch">\n</span><span class="st">'</span>, subset <span class="op">&gt;</span> <span class="dv">10000</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="co"># Use a subset of data to keep output readable.</span></span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>subset <span class="op">=</span> data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>]</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Subset of data:</span><span class="ch">\n</span><span class="st">'</span>, subset)</span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a></span>
+<span id="cb15-5"><a href="#cb15-5" tabindex="-1"></a><span class="co"># Which values were greater than 10000 ?</span></span>
+<span id="cb15-6"><a href="#cb15-6" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'</span><span class="ch">\n</span><span class="st">Where are values large?</span><span class="ch">\n</span><span class="st">'</span>, subset <span class="op">&gt;</span> <span class="dv">10000</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4670,8 +4671,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>mask <span class="op">=</span> subset <span class="op">&gt;</span> <span class="dv">10000</span></span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(subset[mask])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>mask <span class="op">=</span> subset <span class="op">&gt;</span> <span class="dv">10000</span></span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a><span class="bu">print</span>(subset[mask])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4693,7 +4694,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(subset[subset <span class="op">&gt;</span> <span class="dv">10000</span>].describe())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="bu">print</span>(subset[subset <span class="op">&gt;</span> <span class="dv">10000</span>].describe())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4727,9 +4728,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a>mask_higher <span class="op">=</span> data <span class="op">&gt;</span> data.mean()</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a>wealth_score <span class="op">=</span> mask_higher.aggregate(<span class="st">'sum'</span>, axis<span class="op">=</span><span class="dv">1</span>) <span class="op">/</span> <span class="bu">len</span>(data.columns)</span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(wealth_score)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a>mask_higher <span class="op">=</span> data <span class="op">&gt;</span> data.mean()</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a>wealth_score <span class="op">=</span> mask_higher.aggregate(<span class="st">'sum'</span>, axis<span class="op">=</span><span class="dv">1</span>) <span class="op">/</span> <span class="bu">len</span>(data.columns)</span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="bu">print</span>(wealth_score)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4773,7 +4774,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.groupby(wealth_score).<span class="bu">sum</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="bu">print</span>(data.groupby(wealth_score).<span class="bu">sum</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4809,9 +4810,9 @@ <h3 class="callout-title">Selection of Individual Values<a class="anchor" aria-l
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a></span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
 </div>
 <p>Write an expression to find the Per Capita GDP of Serbia in 2007.</p>
 </div>
@@ -4822,14 +4823,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The selection can be done by using the labels for both the row
 (“Serbia”) and the column (“gdpPercap_2007”):</p>
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Serbia'</span>, <span class="st">'gdpPercap_2007'</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Serbia'</span>, <span class="st">'gdpPercap_2007'</span>])</span></code></pre>
 </div>
 <p>The output is</p>
 <div class="codewrapper">
@@ -4857,8 +4858,8 @@ <h3 class="callout-title">Extent of Slicing<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_europe.iloc[<span class="dv">0</span>:<span class="dv">2</span>, <span class="dv">0</span>:<span class="dv">2</span>])</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Albania'</span>:<span class="st">'Belgium'</span>, <span class="st">'gdpPercap_1952'</span>:<span class="st">'gdpPercap_1962'</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a><span class="bu">print</span>(data_europe.iloc[<span class="dv">0</span>:<span class="dv">2</span>, <span class="dv">0</span>:<span class="dv">2</span>])</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Albania'</span>:<span class="st">'Belgium'</span>, <span class="st">'gdpPercap_1952'</span>:<span class="st">'gdpPercap_1962'</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -4868,7 +4869,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>No, they do not produce the same output! The output of the first
 statement is:</p>
@@ -4913,11 +4914,11 @@ <h3 class="callout-title">Reconstructing Data<a class="anchor" aria-label="ancho
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span>
-<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span>
-<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span>
-<span id="cb31-5"><a href="#cb31-5" aria-hidden="true" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span>
+<span id="cb31-3"><a href="#cb31-3" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span>
+<span id="cb31-4"><a href="#cb31-4" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span>
+<span id="cb31-5"><a href="#cb31-5" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -4927,13 +4928,13 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Let’s go through this piece of code line by line.</p>
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
 </div>
 <p>This line loads the dataset containing the GDP data from all
 countries into a dataframe called <code>first</code>. The
@@ -4942,7 +4943,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb33">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span></code></pre>
 </div>
 <p>This line makes a selection: only those rows of <code>first</code>
 for which the ‘continent’ column matches ‘Americas’ are extracted.
@@ -4954,7 +4955,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span></code></pre>
 </div>
 <p>As the syntax suggests, this line drops the row from
 <code>second</code> where the label is ‘Puerto Rico’. The resulting
@@ -4963,7 +4964,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span></code></pre>
 </div>
 <p>Again we apply the drop function, but in this case we are dropping
 not a row but a whole column. To accomplish this, we need to specify
@@ -4972,7 +4973,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb36">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" aria-hidden="true" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
 </div>
 <p>The final step is to write the data that we have been working on to a
 csv file. Pandas makes this easy with the <code>to_csv()</code>
@@ -4997,9 +4998,9 @@ <h3 class="callout-title">Selecting Indices<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb37-2"><a href="#cb37-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.idxmin())</span>
-<span id="cb37-3"><a href="#cb37-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.idxmax())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb37-2"><a href="#cb37-2" tabindex="-1"></a><span class="bu">print</span>(data.idxmin())</span>
+<span id="cb37-3"><a href="#cb37-3" tabindex="-1"></a><span class="bu">print</span>(data.idxmax())</span></code></pre>
 </div>
 </div>
 </div>
@@ -5009,7 +5010,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>For each column in <code>data</code>, <code>idxmin</code> will return
 the index value corresponding to each column’s minimum;
@@ -5047,25 +5048,25 @@ <h3 class="callout-title">Practice with Selection<a class="anchor" aria-label="a
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>1:</p>
 <div class="codewrapper sourceCode" id="cb38">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a>data[<span class="st">'gdpPercap_1982'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" tabindex="-1"></a>data[<span class="st">'gdpPercap_1982'</span>]</span></code></pre>
 </div>
 <p>2:</p>
 <div class="codewrapper sourceCode" id="cb39">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">'Denmark'</span>,:]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" tabindex="-1"></a>data.loc[<span class="st">'Denmark'</span>,:]</span></code></pre>
 </div>
 <p>3:</p>
 <div class="codewrapper sourceCode" id="cb40">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a>data.loc[:,<span class="st">'gdpPercap_1985'</span>:]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" tabindex="-1"></a>data.loc[:,<span class="st">'gdpPercap_1985'</span>:]</span></code></pre>
 </div>
 <p>Pandas is smart enough to recognize the number at the end of the
 column label and does not give you an error, although no column named
@@ -5075,7 +5076,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb41">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" aria-hidden="true" tabindex="-1"></a>data[<span class="st">'gdpPercap_2007'</span>]<span class="op">/</span>data[<span class="st">'gdpPercap_1952'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" tabindex="-1"></a>data[<span class="st">'gdpPercap_2007'</span>]<span class="op">/</span>data[<span class="st">'gdpPercap_1952'</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -5112,141 +5113,141 @@ <h3 class="callout-title">Many Ways of Access<a class="anchor" aria-label="ancho
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Show me the solution</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <p>1. Access a single column:</p>
 <div class="codewrapper sourceCode" id="cb42">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb42-2"><a href="#cb42-2" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"col_name"</span>]   <span class="co"># as a Series</span></span>
-<span id="cb42-3"><a href="#cb42-3" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]] <span class="co"># as a DataFrame</span></span>
-<span id="cb42-4"><a href="#cb42-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-5"><a href="#cb42-5" aria-hidden="true" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
-<span id="cb42-6"><a href="#cb42-6" aria-hidden="true" tabindex="-1"></a>data.T.loc[<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb42-7"><a href="#cb42-7" aria-hidden="true" tabindex="-1"></a>data.T.loc[[<span class="st">"col_name"</span>]].T  <span class="co"># as a DataFrame</span></span>
-<span id="cb42-8"><a href="#cb42-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-9"><a href="#cb42-9" aria-hidden="true" tabindex="-1"></a><span class="co"># Dot notation (Series)</span></span>
-<span id="cb42-10"><a href="#cb42-10" aria-hidden="true" tabindex="-1"></a>data.col_name</span>
-<span id="cb42-11"><a href="#cb42-11" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-12"><a href="#cb42-12" aria-hidden="true" tabindex="-1"></a><span class="co"># by index (iloc)</span></span>
-<span id="cb42-13"><a href="#cb42-13" aria-hidden="true" tabindex="-1"></a>data.iloc[:, col_index]   <span class="co"># as a Series</span></span>
-<span id="cb42-14"><a href="#cb42-14" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col_index]] <span class="co"># as a DataFrame</span></span>
-<span id="cb42-15"><a href="#cb42-15" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-16"><a href="#cb42-16" aria-hidden="true" tabindex="-1"></a><span class="co"># using a mask</span></span>
-<span id="cb42-17"><a href="#cb42-17" aria-hidden="true" tabindex="-1"></a>data.T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb42-2"><a href="#cb42-2" tabindex="-1"></a>data[<span class="st">"col_name"</span>]   <span class="co"># as a Series</span></span>
+<span id="cb42-3"><a href="#cb42-3" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]] <span class="co"># as a DataFrame</span></span>
+<span id="cb42-4"><a href="#cb42-4" tabindex="-1"></a></span>
+<span id="cb42-5"><a href="#cb42-5" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
+<span id="cb42-6"><a href="#cb42-6" tabindex="-1"></a>data.T.loc[<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb42-7"><a href="#cb42-7" tabindex="-1"></a>data.T.loc[[<span class="st">"col_name"</span>]].T  <span class="co"># as a DataFrame</span></span>
+<span id="cb42-8"><a href="#cb42-8" tabindex="-1"></a></span>
+<span id="cb42-9"><a href="#cb42-9" tabindex="-1"></a><span class="co"># Dot notation (Series)</span></span>
+<span id="cb42-10"><a href="#cb42-10" tabindex="-1"></a>data.col_name</span>
+<span id="cb42-11"><a href="#cb42-11" tabindex="-1"></a></span>
+<span id="cb42-12"><a href="#cb42-12" tabindex="-1"></a><span class="co"># by index (iloc)</span></span>
+<span id="cb42-13"><a href="#cb42-13" tabindex="-1"></a>data.iloc[:, col_index]   <span class="co"># as a Series</span></span>
+<span id="cb42-14"><a href="#cb42-14" tabindex="-1"></a>data.iloc[:, [col_index]] <span class="co"># as a DataFrame</span></span>
+<span id="cb42-15"><a href="#cb42-15" tabindex="-1"></a></span>
+<span id="cb42-16"><a href="#cb42-16" tabindex="-1"></a><span class="co"># using a mask</span></span>
+<span id="cb42-17"><a href="#cb42-17" tabindex="-1"></a>data.T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
 </div>
 <p>2. Access a single row:</p>
 <div class="codewrapper sourceCode" id="cb43">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
-<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
-<span id="cb43-3"><a href="#cb43-3" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]] <span class="co"># as a DataFrame</span></span>
-<span id="cb43-4"><a href="#cb43-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb43-5"><a href="#cb43-5" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb43-6"><a href="#cb43-6" aria-hidden="true" tabindex="-1"></a>data.T[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
-<span id="cb43-7"><a href="#cb43-7" aria-hidden="true" tabindex="-1"></a>data.T[[<span class="st">"row_name"</span>]].T <span class="co"># as a DataFrame</span></span>
-<span id="cb43-8"><a href="#cb43-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb43-9"><a href="#cb43-9" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb43-10"><a href="#cb43-10" aria-hidden="true" tabindex="-1"></a>data.iloc[row_index]   <span class="co"># as a Series</span></span>
-<span id="cb43-11"><a href="#cb43-11" aria-hidden="true" tabindex="-1"></a>data.iloc[[row_index]]   <span class="co"># as a DataFrame</span></span>
-<span id="cb43-12"><a href="#cb43-12" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb43-13"><a href="#cb43-13" aria-hidden="true" tabindex="-1"></a><span class="co"># using mask</span></span>
-<span id="cb43-14"><a href="#cb43-14" aria-hidden="true" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
+<span id="cb43-2"><a href="#cb43-2" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
+<span id="cb43-3"><a href="#cb43-3" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]] <span class="co"># as a DataFrame</span></span>
+<span id="cb43-4"><a href="#cb43-4" tabindex="-1"></a></span>
+<span id="cb43-5"><a href="#cb43-5" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb43-6"><a href="#cb43-6" tabindex="-1"></a>data.T[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
+<span id="cb43-7"><a href="#cb43-7" tabindex="-1"></a>data.T[[<span class="st">"row_name"</span>]].T <span class="co"># as a DataFrame</span></span>
+<span id="cb43-8"><a href="#cb43-8" tabindex="-1"></a></span>
+<span id="cb43-9"><a href="#cb43-9" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb43-10"><a href="#cb43-10" tabindex="-1"></a>data.iloc[row_index]   <span class="co"># as a Series</span></span>
+<span id="cb43-11"><a href="#cb43-11" tabindex="-1"></a>data.iloc[[row_index]]   <span class="co"># as a DataFrame</span></span>
+<span id="cb43-12"><a href="#cb43-12" tabindex="-1"></a></span>
+<span id="cb43-13"><a href="#cb43-13" tabindex="-1"></a><span class="co"># using mask</span></span>
+<span id="cb43-14"><a href="#cb43-14" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>]</span></code></pre>
 </div>
 <p>3. Access an individual DataFrame element:</p>
 <div class="codewrapper sourceCode" id="cb44">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by column/row names</span></span>
-<span id="cb44-2"><a href="#cb44-2" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"column_name"</span>][<span class="st">"row_name"</span>]         <span class="co"># as a Series</span></span>
-<span id="cb44-3"><a href="#cb44-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-4"><a href="#cb44-4" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb44-5"><a href="#cb44-5" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
-<span id="cb44-6"><a href="#cb44-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-7"><a href="#cb44-7" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>][<span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
-<span id="cb44-8"><a href="#cb44-8" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb44-9"><a href="#cb44-9" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][[<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame</span></span>
-<span id="cb44-10"><a href="#cb44-10" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-11"><a href="#cb44-11" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, <span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
-<span id="cb44-12"><a href="#cb44-12" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], <span class="st">"col_name"</span>]  <span class="co"># as a Series. Preserves index. Column name is moved to `.name`.</span></span>
-<span id="cb44-13"><a href="#cb44-13" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, [<span class="st">"col_name"</span>]]  <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
-<span id="cb44-14"><a href="#cb44-14" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], [<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
-<span id="cb44-15"><a href="#cb44-15" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-16"><a href="#cb44-16" aria-hidden="true" tabindex="-1"></a><span class="co"># by column/row names: Dot notation</span></span>
-<span id="cb44-17"><a href="#cb44-17" aria-hidden="true" tabindex="-1"></a>data.col_name.row_name</span>
-<span id="cb44-18"><a href="#cb44-18" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-19"><a href="#cb44-19" aria-hidden="true" tabindex="-1"></a><span class="co"># by column/row indices</span></span>
-<span id="cb44-20"><a href="#cb44-20" aria-hidden="true" tabindex="-1"></a>data.iloc[row_index, col_index] <span class="co"># as a value</span></span>
-<span id="cb44-21"><a href="#cb44-21" aria-hidden="true" tabindex="-1"></a>data.iloc[[row_index], col_index] <span class="co"># as a Series. Preserves index. Column name is moved to `.name`</span></span>
-<span id="cb44-22"><a href="#cb44-22" aria-hidden="true" tabindex="-1"></a>data.iloc[row_index, [col_index]] <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
-<span id="cb44-23"><a href="#cb44-23" aria-hidden="true" tabindex="-1"></a>data.iloc[[row_index], [col_index]] <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
-<span id="cb44-24"><a href="#cb44-24" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-25"><a href="#cb44-25" aria-hidden="true" tabindex="-1"></a><span class="co"># column name + row index</span></span>
-<span id="cb44-26"><a href="#cb44-26" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"col_name"</span>][row_index]</span>
-<span id="cb44-27"><a href="#cb44-27" aria-hidden="true" tabindex="-1"></a>data.col_name[row_index]</span>
-<span id="cb44-28"><a href="#cb44-28" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"col_name"</span>].iloc[row_index]</span>
-<span id="cb44-29"><a href="#cb44-29" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-30"><a href="#cb44-30" aria-hidden="true" tabindex="-1"></a><span class="co"># column index + row name</span></span>
-<span id="cb44-31"><a href="#cb44-31" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col_index]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb44-32"><a href="#cb44-32" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col_index]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
-<span id="cb44-33"><a href="#cb44-33" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-34"><a href="#cb44-34" aria-hidden="true" tabindex="-1"></a><span class="co"># using masks</span></span>
-<span id="cb44-35"><a href="#cb44-35" aria-hidden="true" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>].T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" tabindex="-1"></a><span class="co"># by column/row names</span></span>
+<span id="cb44-2"><a href="#cb44-2" tabindex="-1"></a>data[<span class="st">"column_name"</span>][<span class="st">"row_name"</span>]         <span class="co"># as a Series</span></span>
+<span id="cb44-3"><a href="#cb44-3" tabindex="-1"></a></span>
+<span id="cb44-4"><a href="#cb44-4" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb44-5"><a href="#cb44-5" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
+<span id="cb44-6"><a href="#cb44-6" tabindex="-1"></a></span>
+<span id="cb44-7"><a href="#cb44-7" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>][<span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
+<span id="cb44-8"><a href="#cb44-8" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb44-9"><a href="#cb44-9" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][[<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame</span></span>
+<span id="cb44-10"><a href="#cb44-10" tabindex="-1"></a></span>
+<span id="cb44-11"><a href="#cb44-11" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, <span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
+<span id="cb44-12"><a href="#cb44-12" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], <span class="st">"col_name"</span>]  <span class="co"># as a Series. Preserves index. Column name is moved to `.name`.</span></span>
+<span id="cb44-13"><a href="#cb44-13" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, [<span class="st">"col_name"</span>]]  <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
+<span id="cb44-14"><a href="#cb44-14" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], [<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
+<span id="cb44-15"><a href="#cb44-15" tabindex="-1"></a></span>
+<span id="cb44-16"><a href="#cb44-16" tabindex="-1"></a><span class="co"># by column/row names: Dot notation</span></span>
+<span id="cb44-17"><a href="#cb44-17" tabindex="-1"></a>data.col_name.row_name</span>
+<span id="cb44-18"><a href="#cb44-18" tabindex="-1"></a></span>
+<span id="cb44-19"><a href="#cb44-19" tabindex="-1"></a><span class="co"># by column/row indices</span></span>
+<span id="cb44-20"><a href="#cb44-20" tabindex="-1"></a>data.iloc[row_index, col_index] <span class="co"># as a value</span></span>
+<span id="cb44-21"><a href="#cb44-21" tabindex="-1"></a>data.iloc[[row_index], col_index] <span class="co"># as a Series. Preserves index. Column name is moved to `.name`</span></span>
+<span id="cb44-22"><a href="#cb44-22" tabindex="-1"></a>data.iloc[row_index, [col_index]] <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
+<span id="cb44-23"><a href="#cb44-23" tabindex="-1"></a>data.iloc[[row_index], [col_index]] <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
+<span id="cb44-24"><a href="#cb44-24" tabindex="-1"></a></span>
+<span id="cb44-25"><a href="#cb44-25" tabindex="-1"></a><span class="co"># column name + row index</span></span>
+<span id="cb44-26"><a href="#cb44-26" tabindex="-1"></a>data[<span class="st">"col_name"</span>][row_index]</span>
+<span id="cb44-27"><a href="#cb44-27" tabindex="-1"></a>data.col_name[row_index]</span>
+<span id="cb44-28"><a href="#cb44-28" tabindex="-1"></a>data[<span class="st">"col_name"</span>].iloc[row_index]</span>
+<span id="cb44-29"><a href="#cb44-29" tabindex="-1"></a></span>
+<span id="cb44-30"><a href="#cb44-30" tabindex="-1"></a><span class="co"># column index + row name</span></span>
+<span id="cb44-31"><a href="#cb44-31" tabindex="-1"></a>data.iloc[:, [col_index]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb44-32"><a href="#cb44-32" tabindex="-1"></a>data.iloc[:, [col_index]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
+<span id="cb44-33"><a href="#cb44-33" tabindex="-1"></a></span>
+<span id="cb44-34"><a href="#cb44-34" tabindex="-1"></a><span class="co"># using masks</span></span>
+<span id="cb44-35"><a href="#cb44-35" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>].T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
 </div>
 <p>4. Access several columns:</p>
 <div class="codewrapper sourceCode" id="cb45">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb45-1"><a href="#cb45-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb45-2"><a href="#cb45-2" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
-<span id="cb45-3"><a href="#cb45-3" aria-hidden="true" tabindex="-1"></a>data.loc[:, [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
-<span id="cb45-4"><a href="#cb45-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb45-5"><a href="#cb45-5" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb45-6"><a href="#cb45-6" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb45-1"><a href="#cb45-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb45-2"><a href="#cb45-2" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
+<span id="cb45-3"><a href="#cb45-3" tabindex="-1"></a>data.loc[:, [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
+<span id="cb45-4"><a href="#cb45-4" tabindex="-1"></a></span>
+<span id="cb45-5"><a href="#cb45-5" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb45-6"><a href="#cb45-6" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]]</span></code></pre>
 </div>
 <p>5. Access several rows</p>
 <div class="codewrapper sourceCode" id="cb46">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb46-2"><a href="#cb46-2" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span>
-<span id="cb46-3"><a href="#cb46-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb46-4"><a href="#cb46-4" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb46-5"><a href="#cb46-5" aria-hidden="true" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index]]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb46-2"><a href="#cb46-2" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span>
+<span id="cb46-3"><a href="#cb46-3" tabindex="-1"></a></span>
+<span id="cb46-4"><a href="#cb46-4" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb46-5"><a href="#cb46-5" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index]]</span></code></pre>
 </div>
 <p>6. Access a subset of specific rows and columns</p>
 <div class="codewrapper sourceCode" id="cb47">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb47-1"><a href="#cb47-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by names</span></span>
-<span id="cb47-2"><a href="#cb47-2" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>], [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
-<span id="cb47-3"><a href="#cb47-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb47-4"><a href="#cb47-4" aria-hidden="true" tabindex="-1"></a><span class="co"># by indices</span></span>
-<span id="cb47-5"><a href="#cb47-5" aria-hidden="true" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index], [col1_index, col2_index, col3_index]]</span>
-<span id="cb47-6"><a href="#cb47-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb47-7"><a href="#cb47-7" aria-hidden="true" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
-<span id="cb47-8"><a href="#cb47-8" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]].iloc[[row1_index, row2_index, row3_index]]</span>
-<span id="cb47-9"><a href="#cb47-9" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb47-10"><a href="#cb47-10" aria-hidden="true" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
-<span id="cb47-11"><a href="#cb47-11" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]].loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb47-1"><a href="#cb47-1" tabindex="-1"></a><span class="co"># by names</span></span>
+<span id="cb47-2"><a href="#cb47-2" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>], [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
+<span id="cb47-3"><a href="#cb47-3" tabindex="-1"></a></span>
+<span id="cb47-4"><a href="#cb47-4" tabindex="-1"></a><span class="co"># by indices</span></span>
+<span id="cb47-5"><a href="#cb47-5" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index], [col1_index, col2_index, col3_index]]</span>
+<span id="cb47-6"><a href="#cb47-6" tabindex="-1"></a></span>
+<span id="cb47-7"><a href="#cb47-7" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
+<span id="cb47-8"><a href="#cb47-8" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]].iloc[[row1_index, row2_index, row3_index]]</span>
+<span id="cb47-9"><a href="#cb47-9" tabindex="-1"></a></span>
+<span id="cb47-10"><a href="#cb47-10" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
+<span id="cb47-11"><a href="#cb47-11" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]].loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span></code></pre>
 </div>
 <p>7. Access a subset of row and column ranges</p>
 <div class="codewrapper sourceCode" id="cb48">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb48-2"><a href="#cb48-2" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>, <span class="st">"col1"</span>:<span class="st">"col2"</span>]</span>
-<span id="cb48-3"><a href="#cb48-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb48-4"><a href="#cb48-4" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb48-5"><a href="#cb48-5" aria-hidden="true" tabindex="-1"></a>data.iloc[row1_index:row2_index, col1_index:col2_index]</span>
-<span id="cb48-6"><a href="#cb48-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb48-7"><a href="#cb48-7" aria-hidden="true" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
-<span id="cb48-8"><a href="#cb48-8" aria-hidden="true" tabindex="-1"></a>data.loc[:, <span class="st">"col1_name"</span>:<span class="st">"col2_name"</span>].iloc[row1_index:row2_index]</span>
-<span id="cb48-9"><a href="#cb48-9" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb48-10"><a href="#cb48-10" aria-hidden="true" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
-<span id="cb48-11"><a href="#cb48-11" aria-hidden="true" tabindex="-1"></a>data.iloc[:, col1_index:col2_index].loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb48-2"><a href="#cb48-2" tabindex="-1"></a>data.loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>, <span class="st">"col1"</span>:<span class="st">"col2"</span>]</span>
+<span id="cb48-3"><a href="#cb48-3" tabindex="-1"></a></span>
+<span id="cb48-4"><a href="#cb48-4" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb48-5"><a href="#cb48-5" tabindex="-1"></a>data.iloc[row1_index:row2_index, col1_index:col2_index]</span>
+<span id="cb48-6"><a href="#cb48-6" tabindex="-1"></a></span>
+<span id="cb48-7"><a href="#cb48-7" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
+<span id="cb48-8"><a href="#cb48-8" tabindex="-1"></a>data.loc[:, <span class="st">"col1_name"</span>:<span class="st">"col2_name"</span>].iloc[row1_index:row2_index]</span>
+<span id="cb48-9"><a href="#cb48-9" tabindex="-1"></a></span>
+<span id="cb48-10"><a href="#cb48-10" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
+<span id="cb48-11"><a href="#cb48-11" tabindex="-1"></a>data.iloc[:, col1_index:col2_index].loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -5267,22 +5268,22 @@ <h3 class="callout-title">Exploring available methods using the<code>dir()</code
 <div class="codewrapper sourceCode" id="cb49">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb49-1"><a href="#cb49-1" aria-hidden="true" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>   <span class="co"># creation of a string object </span></span>
-<span id="cb49-2"><a href="#cb49-2" aria-hidden="true" tabindex="-1"></a><span class="bu">dir</span>(my_string)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb49-1"><a href="#cb49-1" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>   <span class="co"># creation of a string object </span></span>
+<span id="cb49-2"><a href="#cb49-2" tabindex="-1"></a><span class="bu">dir</span>(my_string)</span></code></pre>
 </div>
 <p>This command returns:</p>
 <div class="codewrapper sourceCode" id="cb50">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb50-1"><a href="#cb50-1" aria-hidden="true" tabindex="-1"></a>[<span class="st">'__add__'</span>,</span>
-<span id="cb50-2"><a href="#cb50-2" aria-hidden="true" tabindex="-1"></a>...</span>
-<span id="cb50-3"><a href="#cb50-3" aria-hidden="true" tabindex="-1"></a><span class="st">'__subclasshook__'</span>,</span>
-<span id="cb50-4"><a href="#cb50-4" aria-hidden="true" tabindex="-1"></a><span class="st">'capitalize'</span>,</span>
-<span id="cb50-5"><a href="#cb50-5" aria-hidden="true" tabindex="-1"></a><span class="st">'casefold'</span>,</span>
-<span id="cb50-6"><a href="#cb50-6" aria-hidden="true" tabindex="-1"></a><span class="st">'center'</span>,</span>
-<span id="cb50-7"><a href="#cb50-7" aria-hidden="true" tabindex="-1"></a>...</span>
-<span id="cb50-8"><a href="#cb50-8" aria-hidden="true" tabindex="-1"></a><span class="st">'upper'</span>,</span>
-<span id="cb50-9"><a href="#cb50-9" aria-hidden="true" tabindex="-1"></a><span class="st">'zfill'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb50-1"><a href="#cb50-1" tabindex="-1"></a>[<span class="st">'__add__'</span>,</span>
+<span id="cb50-2"><a href="#cb50-2" tabindex="-1"></a>...</span>
+<span id="cb50-3"><a href="#cb50-3" tabindex="-1"></a><span class="st">'__subclasshook__'</span>,</span>
+<span id="cb50-4"><a href="#cb50-4" tabindex="-1"></a><span class="st">'capitalize'</span>,</span>
+<span id="cb50-5"><a href="#cb50-5" tabindex="-1"></a><span class="st">'casefold'</span>,</span>
+<span id="cb50-6"><a href="#cb50-6" tabindex="-1"></a><span class="st">'center'</span>,</span>
+<span id="cb50-7"><a href="#cb50-7" tabindex="-1"></a>...</span>
+<span id="cb50-8"><a href="#cb50-8" tabindex="-1"></a><span class="st">'upper'</span>,</span>
+<span id="cb50-9"><a href="#cb50-9" tabindex="-1"></a><span class="st">'zfill'</span>]</span></code></pre>
 </div>
 <p>You can use <code>help()</code> or <kbd>Shift</kbd>+<kbd>Tab</kbd> to
 get more information about what these methods do.</p>
@@ -5298,14 +5299,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
 <div class="accordion-body">
 <p>Among many choices, <code>dir()</code> lists the
 <code>median()</code> function as a possibility. Thus,</p>
 <div class="codewrapper sourceCode" id="cb51">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb51-1"><a href="#cb51-1" aria-hidden="true" tabindex="-1"></a>data.median()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb51-1"><a href="#cb51-1" tabindex="-1"></a>data.median()</span></code></pre>
 </div>
 </div>
 </div>
@@ -5395,7 +5396,7 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span></code></pre>
 </div>
 <ul>
 <li>Simple plots are then (fairly) simple to create.</li>
@@ -5403,19 +5404,19 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a>time <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>]</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>position <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">100</span>, <span class="dv">200</span>, <span class="dv">300</span>]</span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a>plt.plot(time, position)</span>
-<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a>plt.xlabel(<span class="st">'Time (hr)'</span>)</span>
-<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'Position (km)'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a>time <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>]</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a>position <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">100</span>, <span class="dv">200</span>, <span class="dv">300</span>]</span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a></span>
+<span id="cb2-4"><a href="#cb2-4" tabindex="-1"></a>plt.plot(time, position)</span>
+<span id="cb2-5"><a href="#cb2-5" tabindex="-1"></a>plt.xlabel(<span class="st">'Time (hr)'</span>)</span>
+<span id="cb2-6"><a href="#cb2-6" tabindex="-1"></a>plt.ylabel(<span class="st">'Position (km)'</span>)</span></code></pre>
 </div>
-<figure><img src="fig/9_simple_position_time_plot.svg" alt="Simple Position-Time Plot" class="figure mx-auto d-block"></figure><div id="display-all-open-figures" class="callout callout">
+<figure><img src="fig/9_simple_position_time_plot.svg" alt="Simple Position-Time Plot" class="figure mx-auto d-block"></figure><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="display-all-open-figures" class="callout-inner">
-<h3 class="callout-title">Display All Open Figures<a class="anchor" aria-label="anchor" href="#display-all-open-figures"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="display-all-open-figures">Display All Open Figures<a class="anchor" aria-label="anchor" href="#display-all-open-figures"></a>
 </h3>
 <div class="callout-content">
 <p>In our Jupyter Notebook example, running the cell should generate the
@@ -5428,7 +5429,7 @@ <h3 class="callout-title">Display All Open Figures<a class="anchor" aria-label="
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>plt.show()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a>plt.show()</span></code></pre>
 </div>
 <p>This command can also be used within a Notebook - for instance, to
 display multiple figures if several are created by a single cell.</p>
@@ -5452,23 +5453,23 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-5"><a href="#cb4-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Extract year from last 4 characters of each column name</span></span>
-<span id="cb4-6"><a href="#cb4-6" aria-hidden="true" tabindex="-1"></a><span class="co"># The current column names are structured as 'gdpPercap_(year)', </span></span>
-<span id="cb4-7"><a href="#cb4-7" aria-hidden="true" tabindex="-1"></a><span class="co"># so we want to keep the (year) part only for clarity when plotting GDP vs. years</span></span>
-<span id="cb4-8"><a href="#cb4-8" aria-hidden="true" tabindex="-1"></a><span class="co"># To do this we use replace(), which removes from the string the characters stated in the argument</span></span>
-<span id="cb4-9"><a href="#cb4-9" aria-hidden="true" tabindex="-1"></a><span class="co"># This method works on strings, so we use replace() from Pandas Series.str vectorized string functions</span></span>
-<span id="cb4-10"><a href="#cb4-10" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-11"><a href="#cb4-11" aria-hidden="true" tabindex="-1"></a>years <span class="op">=</span> data.columns.<span class="bu">str</span>.replace(<span class="st">'gdpPercap_'</span>, <span class="st">''</span>)</span>
-<span id="cb4-12"><a href="#cb4-12" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-13"><a href="#cb4-13" aria-hidden="true" tabindex="-1"></a><span class="co"># Convert year values to integers, saving results back to dataframe</span></span>
-<span id="cb4-14"><a href="#cb4-14" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-15"><a href="#cb4-15" aria-hidden="true" tabindex="-1"></a>data.columns <span class="op">=</span> years.astype(<span class="bu">int</span>)</span>
-<span id="cb4-16"><a href="#cb4-16" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-17"><a href="#cb4-17" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">'Australia'</span>].plot()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a></span>
+<span id="cb4-3"><a href="#cb4-3" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb4-4"><a href="#cb4-4" tabindex="-1"></a></span>
+<span id="cb4-5"><a href="#cb4-5" tabindex="-1"></a><span class="co"># Extract year from last 4 characters of each column name</span></span>
+<span id="cb4-6"><a href="#cb4-6" tabindex="-1"></a><span class="co"># The current column names are structured as 'gdpPercap_(year)', </span></span>
+<span id="cb4-7"><a href="#cb4-7" tabindex="-1"></a><span class="co"># so we want to keep the (year) part only for clarity when plotting GDP vs. years</span></span>
+<span id="cb4-8"><a href="#cb4-8" tabindex="-1"></a><span class="co"># To do this we use replace(), which removes from the string the characters stated in the argument</span></span>
+<span id="cb4-9"><a href="#cb4-9" tabindex="-1"></a><span class="co"># This method works on strings, so we use replace() from Pandas Series.str vectorized string functions</span></span>
+<span id="cb4-10"><a href="#cb4-10" tabindex="-1"></a></span>
+<span id="cb4-11"><a href="#cb4-11" tabindex="-1"></a>years <span class="op">=</span> data.columns.<span class="bu">str</span>.replace(<span class="st">'gdpPercap_'</span>, <span class="st">''</span>)</span>
+<span id="cb4-12"><a href="#cb4-12" tabindex="-1"></a></span>
+<span id="cb4-13"><a href="#cb4-13" tabindex="-1"></a><span class="co"># Convert year values to integers, saving results back to dataframe</span></span>
+<span id="cb4-14"><a href="#cb4-14" tabindex="-1"></a></span>
+<span id="cb4-15"><a href="#cb4-15" tabindex="-1"></a>data.columns <span class="op">=</span> years.astype(<span class="bu">int</span>)</span>
+<span id="cb4-16"><a href="#cb4-16" tabindex="-1"></a></span>
+<span id="cb4-17"><a href="#cb4-17" tabindex="-1"></a>data.loc[<span class="st">'Australia'</span>].plot()</span></code></pre>
 </div>
 <figure><img src="fig/9_gdp_australia.svg" alt="GDP plot for Australia" class="figure mx-auto d-block"></figure></section><section id="select-and-transform-data-then-plot-it."><h2 class="section-heading">Select and transform data, then plot it.<a class="anchor" aria-label="anchor" href="#select-and-transform-data-then-plot-it."></a>
 </h2>
@@ -5481,8 +5482,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>data.T.plot()</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>data.T.plot()</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
 </div>
 <figure><img src="fig/9_gdp_australia_nz.svg" alt="GDP plot for Australia and New Zealand" class="figure mx-auto d-block"></figure></section><section id="many-styles-of-plot-are-available."><h2 class="section-heading">Many styles of plot are available.<a class="anchor" aria-label="anchor" href="#many-styles-of-plot-are-available."></a>
 </h2>
@@ -5493,9 +5494,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>plt.style.use(<span class="st">'ggplot'</span>)</span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a>data.T.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
-<span id="cb6-3"><a href="#cb6-3" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a>plt.style.use(<span class="st">'ggplot'</span>)</span>
+<span id="cb6-2"><a href="#cb6-2" tabindex="-1"></a>data.T.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
+<span id="cb6-3"><a href="#cb6-3" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
 </div>
 <figure><img src="fig/9_gdp_bar.svg" alt="GDP barplot for Australia" class="figure mx-auto d-block"></figure></section><section id="data-can-also-be-plotted-by-calling-the-matplotlib-plot-function-directly."><h2 class="section-heading">Data can also be plotted by calling the <code>matplotlib</code>
 <code>plot</code> function directly.<a class="anchor" aria-label="anchor" href="#data-can-also-be-plotted-by-calling-the-matplotlib-plot-function-directly."></a>
@@ -5513,10 +5514,10 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>years <span class="op">=</span> data.columns</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'g--'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>years <span class="op">=</span> data.columns</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a></span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'g--'</span>)</span></code></pre>
 </div>
 <figure><img src="fig/9_gdp_australia_formatted.svg" alt="GDP formatted plot for Australia" class="figure mx-auto d-block"></figure></section><section id="can-plot-many-sets-of-data-together."><h2 class="section-heading">Can plot many sets of data together.<a class="anchor" aria-label="anchor" href="#can-plot-many-sets-of-data-together."></a>
 </h2>
@@ -5524,25 +5525,25 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Select two countries' worth of data.</span></span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
-<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a>gdp_nz <span class="op">=</span> data.loc[<span class="st">'New Zealand'</span>]</span>
-<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb8-5"><a href="#cb8-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Plot with differently-colored markers.</span></span>
-<span id="cb8-6"><a href="#cb8-6" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'b-'</span>, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
-<span id="cb8-7"><a href="#cb8-7" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_nz, <span class="st">'g-'</span>, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span>
-<span id="cb8-8"><a href="#cb8-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb8-9"><a href="#cb8-9" aria-hidden="true" tabindex="-1"></a><span class="co"># Create legend.</span></span>
-<span id="cb8-10"><a href="#cb8-10" aria-hidden="true" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'upper left'</span>)</span>
-<span id="cb8-11"><a href="#cb8-11" aria-hidden="true" tabindex="-1"></a>plt.xlabel(<span class="st">'Year'</span>)</span>
-<span id="cb8-12"><a href="#cb8-12" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita ($)'</span>)</span></code></pre>
-</div>
-<div id="adding-a-legend" class="callout callout">
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="co"># Select two countries' worth of data.</span></span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
+<span id="cb8-3"><a href="#cb8-3" tabindex="-1"></a>gdp_nz <span class="op">=</span> data.loc[<span class="st">'New Zealand'</span>]</span>
+<span id="cb8-4"><a href="#cb8-4" tabindex="-1"></a></span>
+<span id="cb8-5"><a href="#cb8-5" tabindex="-1"></a><span class="co"># Plot with differently-colored markers.</span></span>
+<span id="cb8-6"><a href="#cb8-6" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'b-'</span>, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
+<span id="cb8-7"><a href="#cb8-7" tabindex="-1"></a>plt.plot(years, gdp_nz, <span class="st">'g-'</span>, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span>
+<span id="cb8-8"><a href="#cb8-8" tabindex="-1"></a></span>
+<span id="cb8-9"><a href="#cb8-9" tabindex="-1"></a><span class="co"># Create legend.</span></span>
+<span id="cb8-10"><a href="#cb8-10" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'upper left'</span>)</span>
+<span id="cb8-11"><a href="#cb8-11" tabindex="-1"></a>plt.xlabel(<span class="st">'Year'</span>)</span>
+<span id="cb8-12"><a href="#cb8-12" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita ($)'</span>)</span></code></pre>
+</div>
+<div id="callout2" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="adding-a-legend" class="callout-inner">
-<h3 class="callout-title">Adding a Legend<a class="anchor" aria-label="anchor" href="#adding-a-legend"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="adding-a-legend">Adding a Legend<a class="anchor" aria-label="anchor" href="#adding-a-legend"></a>
 </h3>
 <div class="callout-content">
 <p>Often when plotting multiple datasets on the same figure it is
@@ -5554,8 +5555,8 @@ <h3 class="callout-title">Adding a Legend<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_australia, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_nz, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>plt.plot(years, gdp_australia, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>plt.plot(years, gdp_nz, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span></code></pre>
 </div>
 <ul>
 <li>Instruct <code>matplotlib</code> to create the legend.</li>
@@ -5563,7 +5564,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a>plt.legend()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a>plt.legend()</span></code></pre>
 </div>
 <p>By default matplotlib will attempt to place the legend in a suitable
 position. If you would rather specify a position this can be done with
@@ -5582,12 +5583,12 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>plt.scatter(gdp_australia, gdp_nz)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>plt.scatter(gdp_australia, gdp_nz)</span></code></pre>
 </div>
 <figure><img src="fig/9_gdp_correlation_plt.svg" alt="GDP correlation using plt.scatter" class="figure mx-auto d-block"></figure><div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a>data.T.plot.scatter(x <span class="op">=</span> <span class="st">'Australia'</span>, y <span class="op">=</span> <span class="st">'New Zealand'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a>data.T.plot.scatter(x <span class="op">=</span> <span class="st">'Australia'</span>, y <span class="op">=</span> <span class="st">'New Zealand'</span>)</span></code></pre>
 </div>
 <figure><img src="fig/9_gdp_correlation_data.svg" alt="GDP correlation using data.T.plot.scatter" class="figure mx-auto d-block"></figure><div id="minima-and-maxima" class="callout challenge">
 <div class="callout-square">
@@ -5603,11 +5604,11 @@ <h3 class="callout-title">Minima and Maxima<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a>data_europe.____.plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
-<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a>data_europe.____</span>
-<span id="cb13-4"><a href="#cb13-4" aria-hidden="true" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
-<span id="cb13-5"><a href="#cb13-5" aria-hidden="true" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a>data_europe.____.plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
+<span id="cb13-3"><a href="#cb13-3" tabindex="-1"></a>data_europe.____</span>
+<span id="cb13-4"><a href="#cb13-4" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
+<span id="cb13-5"><a href="#cb13-5" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -5617,16 +5618,16 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a>data_europe.<span class="bu">min</span>().plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a>data_europe.<span class="bu">max</span>().plot(label<span class="op">=</span><span class="st">'max'</span>)</span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a>data_europe.<span class="bu">min</span>().plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a>data_europe.<span class="bu">max</span>().plot(label<span class="op">=</span><span class="st">'max'</span>)</span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
 </div>
 <figure><img src="fig/9_minima_maxima_solution.png" alt="Minima Maxima Solution" class="figure mx-auto d-block"></figure>
 </div>
@@ -5653,13 +5654,13 @@ <h3 class="callout-title">Correlations<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>data_asia.describe().T.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'min'</span>, y<span class="op">=</span><span class="st">'max'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>data_asia.describe().T.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'min'</span>, y<span class="op">=</span><span class="st">'max'</span>)</span></code></pre>
 </div>
 <figure><img src="fig/9_correlations_solution1.svg" alt="Correlations Solution 1" class="figure mx-auto d-block"></figure><p>No particular correlations can be seen between the minimum and
 maximum gdp values year on year. It seems the fortunes of asian
@@ -5682,10 +5683,10 @@ <h3 class="callout-title">Correlations<em>(continued)</em><a class="anchor" aria
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a>data_asia.<span class="bu">max</span>().plot()</span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmax())</span>
-<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmin())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a>data_asia.<span class="bu">max</span>().plot()</span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmax())</span>
+<span id="cb16-4"><a href="#cb16-4" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmin())</span></code></pre>
 </div>
 </div>
 </div>
@@ -5695,7 +5696,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <figure><img src="fig/9_correlations_solution2.png" alt="Correlations Solution 2" class="figure mx-auto d-block"></figure><p>Seems the variability in this value is due to a sharp drop after
 1972. Some geopolitics at play perhaps? Given the dominance of oil
@@ -5719,9 +5720,9 @@ <h3 class="callout-title">More Correlations<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>data_all <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>data_all.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'gdpPercap_2007'</span>, y<span class="op">=</span><span class="st">'lifeExp_2007'</span>,</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a>              s<span class="op">=</span>data_all[<span class="st">'pop_2007'</span>]<span class="op">/</span><span class="fl">1e6</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>data_all <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>data_all.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'gdpPercap_2007'</span>, y<span class="op">=</span><span class="st">'lifeExp_2007'</span>,</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a>              s<span class="op">=</span>data_all[<span class="st">'pop_2007'</span>]<span class="op">/</span><span class="fl">1e6</span>)</span></code></pre>
 </div>
 <p>Using online help and other resources, explain what each argument to
 <code>plot</code> does.</p>
@@ -5733,7 +5734,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <figure><img src="fig/9_more_correlations_solution.svg" alt="More Correlations Solution" class="figure mx-auto d-block"></figure><p>A good place to look is the documentation for the plot function -
 help(data_all.plot).</p>
@@ -5748,12 +5749,12 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </div>
 </div>
 </div>
-<div id="saving-your-plot-to-a-file" class="callout callout">
+<div id="callout3" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="saving-your-plot-to-a-file" class="callout-inner">
-<h3 class="callout-title">Saving your plot to a file<a class="anchor" aria-label="anchor" href="#saving-your-plot-to-a-file"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="saving-your-plot-to-a-file">Saving your plot to a file<a class="anchor" aria-label="anchor" href="#saving-your-plot-to-a-file"></a>
 </h3>
 <div class="callout-content">
 <p>If you are satisfied with the plot you see you may want to save it to
@@ -5763,7 +5764,7 @@ <h3 class="callout-title">Saving your plot to a file<a class="anchor" aria-label
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>plt.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>plt.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
 </div>
 <p>will save the current figure to the file <code>my_figure.png</code>.
 The file format will automatically be deduced from the file name
@@ -5782,19 +5783,19 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a>data.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>fig <span class="op">=</span> plt.gcf() <span class="co"># get current figure</span></span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a>fig.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a>data.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>fig <span class="op">=</span> plt.gcf() <span class="co"># get current figure</span></span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a>fig.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
 </div>
 </div>
 </div>
 </div>
-<div id="making-your-plots-accessible" class="callout callout">
+<div id="callout4" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="making-your-plots-accessible" class="callout-inner">
-<h3 class="callout-title">Making your plots accessible<a class="anchor" aria-label="anchor" href="#making-your-plots-accessible"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="making-your-plots-accessible">Making your plots accessible<a class="anchor" aria-label="anchor" href="#making-your-plots-accessible"></a>
 </h3>
 <div class="callout-content">
 <p>Whenever you are generating plots to go into a paper or a
@@ -5911,9 +5912,9 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>pressures <span class="op">=</span> [<span class="fl">0.273</span>, <span class="fl">0.275</span>, <span class="fl">0.277</span>, <span class="fl">0.275</span>, <span class="fl">0.276</span>]</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures:'</span>, pressures)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'length:'</span>, <span class="bu">len</span>(pressures))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>pressures <span class="op">=</span> [<span class="fl">0.273</span>, <span class="fl">0.275</span>, <span class="fl">0.277</span>, <span class="fl">0.275</span>, <span class="fl">0.276</span>]</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures:'</span>, pressures)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'length:'</span>, <span class="bu">len</span>(pressures))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5930,8 +5931,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth item of pressures:'</span>, pressures[<span class="dv">0</span>])</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'fourth item of pressures:'</span>, pressures[<span class="dv">4</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth item of pressures:'</span>, pressures[<span class="dv">0</span>])</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'fourth item of pressures:'</span>, pressures[<span class="dv">4</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5949,8 +5950,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>pressures[<span class="dv">0</span>] <span class="op">=</span> <span class="fl">0.265</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures is now:'</span>, pressures)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>pressures[<span class="dv">0</span>] <span class="op">=</span> <span class="fl">0.265</span></span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures is now:'</span>, pressures)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5967,10 +5968,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is initially:'</span>, primes)</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>primes.append(<span class="dv">7</span>)</span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has become:'</span>, primes)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is initially:'</span>, primes)</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a>primes.append(<span class="dv">7</span>)</span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has become:'</span>, primes)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6002,13 +6003,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>teen_primes <span class="op">=</span> [<span class="dv">11</span>, <span class="dv">13</span>, <span class="dv">17</span>, <span class="dv">19</span>]</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>middle_aged_primes <span class="op">=</span> [<span class="dv">37</span>, <span class="dv">41</span>, <span class="dv">43</span>, <span class="dv">47</span>]</span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is currently:'</span>, primes)</span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a>primes.extend(teen_primes)</span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has now become:'</span>, primes)</span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a>primes.append(middle_aged_primes)</span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has finally become:'</span>, primes)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>teen_primes <span class="op">=</span> [<span class="dv">11</span>, <span class="dv">13</span>, <span class="dv">17</span>, <span class="dv">19</span>]</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>middle_aged_primes <span class="op">=</span> [<span class="dv">37</span>, <span class="dv">41</span>, <span class="dv">43</span>, <span class="dv">47</span>]</span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is currently:'</span>, primes)</span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a>primes.extend(teen_primes)</span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has now become:'</span>, primes)</span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a>primes.append(middle_aged_primes)</span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has finally become:'</span>, primes)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6034,10 +6035,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>, <span class="dv">7</span>, <span class="dv">9</span>]</span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes before removing last item:'</span>, primes)</span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a><span class="kw">del</span> primes[<span class="dv">4</span>]</span>
-<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes after removing last item:'</span>, primes)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>, <span class="dv">7</span>, <span class="dv">9</span>]</span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes before removing last item:'</span>, primes)</span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a><span class="kw">del</span> primes[<span class="dv">4</span>]</span>
+<span id="cb11-4"><a href="#cb11-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes after removing last item:'</span>, primes)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6066,7 +6067,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>goals <span class="op">=</span> [<span class="dv">1</span>, <span class="st">'Create lists.'</span>, <span class="dv">2</span>, <span class="st">'Extract items from lists.'</span>, <span class="dv">3</span>, <span class="st">'Modify lists.'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>goals <span class="op">=</span> [<span class="dv">1</span>, <span class="st">'Create lists.'</span>, <span class="dv">2</span>, <span class="st">'Extract items from lists.'</span>, <span class="dv">3</span>, <span class="st">'Modify lists.'</span>]</span></code></pre>
 </div>
 </section><section id="character-strings-can-be-indexed-like-lists."><h2 class="section-heading">Character strings can be indexed like lists.<a class="anchor" aria-label="anchor" href="#character-strings-can-be-indexed-like-lists."></a>
 </h2>
@@ -6078,9 +6079,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'carbon'</span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth character:'</span>, element[<span class="dv">0</span>])</span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'third character:'</span>, element[<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'carbon'</span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth character:'</span>, element[<span class="dv">0</span>])</span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'third character:'</span>, element[<span class="dv">3</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6106,7 +6107,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>element[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'C'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>element[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'C'</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6131,7 +6132,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'99th element of element is:'</span>, element[<span class="dv">99</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'99th element of element is:'</span>, element[<span class="dv">99</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6151,13 +6152,13 @@ <h3 class="callout-title">Fill in the Blanks<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> ____</span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>values.____(<span class="dv">1</span>)</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a>values.____(<span class="dv">3</span>)</span>
-<span id="cb20-4"><a href="#cb20-4" aria-hidden="true" tabindex="-1"></a>values.____(<span class="dv">5</span>)</span>
-<span id="cb20-5"><a href="#cb20-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
-<span id="cb20-6"><a href="#cb20-6" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> values[____]</span>
-<span id="cb20-7"><a href="#cb20-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>values <span class="op">=</span> ____</span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>values.____(<span class="dv">1</span>)</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a>values.____(<span class="dv">3</span>)</span>
+<span id="cb20-4"><a href="#cb20-4" tabindex="-1"></a>values.____(<span class="dv">5</span>)</span>
+<span id="cb20-5"><a href="#cb20-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
+<span id="cb20-6"><a href="#cb20-6" tabindex="-1"></a>values <span class="op">=</span> values[____]</span>
+<span id="cb20-7"><a href="#cb20-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6178,13 +6179,13 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> []</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>values.append(<span class="dv">1</span>)</span>
-<span id="cb22-3"><a href="#cb22-3" aria-hidden="true" tabindex="-1"></a>values.append(<span class="dv">3</span>)</span>
-<span id="cb22-4"><a href="#cb22-4" aria-hidden="true" tabindex="-1"></a>values.append(<span class="dv">5</span>)</span>
-<span id="cb22-5"><a href="#cb22-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
-<span id="cb22-6"><a href="#cb22-6" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> values[<span class="dv">1</span>:]</span>
-<span id="cb22-7"><a href="#cb22-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>values <span class="op">=</span> []</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>values.append(<span class="dv">1</span>)</span>
+<span id="cb22-3"><a href="#cb22-3" tabindex="-1"></a>values.append(<span class="dv">3</span>)</span>
+<span id="cb22-4"><a href="#cb22-4" tabindex="-1"></a>values.append(<span class="dv">5</span>)</span>
+<span id="cb22-5"><a href="#cb22-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
+<span id="cb22-6"><a href="#cb22-6" tabindex="-1"></a>values <span class="op">=</span> values[<span class="dv">1</span>:]</span>
+<span id="cb22-7"><a href="#cb22-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
 </div>
 </div>
 </div>
@@ -6233,8 +6234,8 @@ <h3 class="callout-title">From Strings to Lists and Back<a class="anchor" aria-l
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'string to list:'</span>, <span class="bu">list</span>(<span class="st">'tin'</span>))</span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'list to string:'</span>, <span class="st">''</span>.join([<span class="st">'g'</span>, <span class="st">'o'</span>, <span class="st">'l'</span>, <span class="st">'d'</span>]))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'string to list:'</span>, <span class="bu">list</span>(<span class="st">'tin'</span>))</span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'list to string:'</span>, <span class="st">''</span>.join([<span class="st">'g'</span>, <span class="st">'o'</span>, <span class="st">'l'</span>, <span class="st">'d'</span>]))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6283,8 +6284,8 @@ <h3 class="callout-title">Working With the End<a class="anchor" aria-label="anch
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'helium'</span></span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'helium'</span></span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>How does Python interpret a negative index?</li>
@@ -6335,9 +6336,9 @@ <h3 class="callout-title">Stepping Through a List<a class="anchor" aria-label="a
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'fluorine'</span></span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="dv">2</span>])</span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'fluorine'</span></span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="dv">2</span>])</span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>If we write a slice as <code>low:high:stride</code>, what does
@@ -6359,8 +6360,8 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>furn</span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>eniroulf</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>furn</span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>eniroulf</span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>
@@ -6387,9 +6388,9 @@ <h3 class="callout-title">Slice Bounds<a class="anchor" aria-label="anchor" href
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'lithium'</span></span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[<span class="dv">0</span>:<span class="dv">20</span>])</span>
-<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'lithium'</span></span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a><span class="bu">print</span>(element[<span class="dv">0</span>:<span class="dv">20</span>])</span>
+<span id="cb28-3"><a href="#cb28-3" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -6427,18 +6428,18 @@ <h3 class="callout-title">Sort and Sorted<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program A</span></span>
-<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb30-3"><a href="#cb30-3" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">sorted</span>(letters)</span>
-<span id="cb30-4"><a href="#cb30-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a><span class="co"># Program A</span></span>
+<span id="cb30-2"><a href="#cb30-2" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb30-3"><a href="#cb30-3" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">sorted</span>(letters)</span>
+<span id="cb30-4"><a href="#cb30-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program B</span></span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> letters.sort()</span>
-<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a><span class="co"># Program B</span></span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb31-3"><a href="#cb31-3" tabindex="-1"></a>result <span class="op">=</span> letters.sort()</span>
+<span id="cb31-4"><a href="#cb31-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -6484,20 +6485,20 @@ <h3 class="callout-title">Copying (or Not)<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program A</span></span>
-<span id="cb34-2"><a href="#cb34-2" aria-hidden="true" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb34-3"><a href="#cb34-3" aria-hidden="true" tabindex="-1"></a>new <span class="op">=</span> old      <span class="co"># simple assignment</span></span>
-<span id="cb34-4"><a href="#cb34-4" aria-hidden="true" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
-<span id="cb34-5"><a href="#cb34-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a><span class="co"># Program A</span></span>
+<span id="cb34-2"><a href="#cb34-2" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb34-3"><a href="#cb34-3" tabindex="-1"></a>new <span class="op">=</span> old      <span class="co"># simple assignment</span></span>
+<span id="cb34-4"><a href="#cb34-4" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
+<span id="cb34-5"><a href="#cb34-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program B</span></span>
-<span id="cb35-2"><a href="#cb35-2" aria-hidden="true" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb35-3"><a href="#cb35-3" aria-hidden="true" tabindex="-1"></a>new <span class="op">=</span> old[:]   <span class="co"># assigning a slice</span></span>
-<span id="cb35-4"><a href="#cb35-4" aria-hidden="true" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
-<span id="cb35-5"><a href="#cb35-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a><span class="co"># Program B</span></span>
+<span id="cb35-2"><a href="#cb35-2" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb35-3"><a href="#cb35-3" tabindex="-1"></a>new <span class="op">=</span> old[:]   <span class="co"># assigning a slice</span></span>
+<span id="cb35-4"><a href="#cb35-4" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
+<span id="cb35-5"><a href="#cb35-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
 </div>
 </div>
 </div>
@@ -6606,8 +6607,8 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 <ul>
 <li>This <code>for</code> loop is equivalent to:</li>
@@ -6615,9 +6616,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">2</span>)</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">3</span>)</span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">2</span>)</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">3</span>)</span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span>)</span></code></pre>
 </div>
 <ul>
 <li>And the <code>for</code> loop’s output is:</li>
@@ -6636,8 +6637,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 <ul>
 <li>The collection, <code>[2, 3, 5]</code>, is what the loop is being
@@ -6668,8 +6669,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="bu">print</span>(number)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6682,8 +6683,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>firstName <span class="op">=</span> <span class="st">"Jon"</span></span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>  lastName <span class="op">=</span> <span class="st">"Smith"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>firstName <span class="op">=</span> <span class="st">"Jon"</span></span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>  lastName <span class="op">=</span> <span class="st">"Smith"</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6710,8 +6711,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> kitten <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(kitten)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="cf">for</span> kitten <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>    <span class="bu">print</span>(kitten)</span></code></pre>
 </div>
 </section><section id="the-body-of-a-loop-can-contain-many-statements."><h2 class="section-heading">The body of a loop can contain many statements.<a class="anchor" aria-label="anchor" href="#the-body-of-a-loop-can-contain-many-statements."></a>
 </h2>
@@ -6723,11 +6724,11 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> p <span class="kw">in</span> primes:</span>
-<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>    squared <span class="op">=</span> p <span class="op">**</span> <span class="dv">2</span></span>
-<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a>    cubed <span class="op">=</span> p <span class="op">**</span> <span class="dv">3</span></span>
-<span id="cb10-5"><a href="#cb10-5" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(p, squared, cubed)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a><span class="cf">for</span> p <span class="kw">in</span> primes:</span>
+<span id="cb10-3"><a href="#cb10-3" tabindex="-1"></a>    squared <span class="op">=</span> p <span class="op">**</span> <span class="dv">2</span></span>
+<span id="cb10-4"><a href="#cb10-4" tabindex="-1"></a>    cubed <span class="op">=</span> p <span class="op">**</span> <span class="dv">3</span></span>
+<span id="cb10-5"><a href="#cb10-5" tabindex="-1"></a>    <span class="bu">print</span>(p, squared, cubed)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6759,9 +6760,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'a range is not a list: range(0, 3)'</span>)</span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>, <span class="dv">3</span>):</span>
-<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'a range is not a list: range(0, 3)'</span>)</span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>, <span class="dv">3</span>):</span>
+<span id="cb12-3"><a href="#cb12-3" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6786,11 +6787,11 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Sum the first 10 integers.</span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a>   total <span class="op">=</span> total <span class="op">+</span> (number <span class="op">+</span> <span class="dv">1</span>)</span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a><span class="co"># Sum the first 10 integers.</span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a>   total <span class="op">=</span> total <span class="op">+</span> (number <span class="op">+</span> <span class="dv">1</span>)</span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6827,7 +6828,7 @@ <h3 class="callout-title">Classifying Errors<a class="anchor" aria-label="anchor
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>An IndentationError is a syntax error. Programs with syntax errors
 cannot be started. A program with a runtime error will start but an
@@ -6850,9 +6851,9 @@ <h3 class="callout-title">Tracing Execution<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> <span class="st">"tin"</span>:</span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> <span class="st">"tin"</span>:</span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="dv">1</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -6862,7 +6863,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <table class="table">
 <thead><tr class="header">
@@ -6917,11 +6918,11 @@ <h3 class="callout-title">Reversing a String<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> ____</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
-<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> ____</span>
-<span id="cb17-5"><a href="#cb17-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>result <span class="op">=</span> ____</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
+<span id="cb17-4"><a href="#cb17-4" tabindex="-1"></a>    result <span class="op">=</span> ____</span>
+<span id="cb17-5"><a href="#cb17-5" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -6931,16 +6932,16 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
-<span id="cb18-2"><a href="#cb18-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb18-3"><a href="#cb18-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
-<span id="cb18-4"><a href="#cb18-4" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> char <span class="op">+</span> result</span>
-<span id="cb18-5"><a href="#cb18-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
+<span id="cb18-2"><a href="#cb18-2" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb18-3"><a href="#cb18-3" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
+<span id="cb18-4"><a href="#cb18-4" tabindex="-1"></a>    result <span class="op">=</span> char <span class="op">+</span> result</span>
+<span id="cb18-5"><a href="#cb18-5" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -6959,11 +6960,11 @@ <h3 class="callout-title">Practice Accumulating<a class="anchor" aria-label="anc
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Total length of the strings in the list: ["red", "green", "blue"] =&gt; 12</span></span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb19-4"><a href="#cb19-4" aria-hidden="true" tabindex="-1"></a>    ____ <span class="op">=</span> ____ <span class="op">+</span> <span class="bu">len</span>(word)</span>
-<span id="cb19-5"><a href="#cb19-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="co"># Total length of the strings in the list: ["red", "green", "blue"] =&gt; 12</span></span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb19-4"><a href="#cb19-4" tabindex="-1"></a>    ____ <span class="op">=</span> ____ <span class="op">+</span> <span class="bu">len</span>(word)</span>
+<span id="cb19-5"><a href="#cb19-5" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
 </div>
 </div>
 </div>
@@ -6973,15 +6974,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="bu">len</span>(word)</span>
-<span id="cb20-4"><a href="#cb20-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="bu">len</span>(word)</span>
+<span id="cb20-4"><a href="#cb20-4" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
 </div>
 </div>
 </div>
@@ -6998,11 +6999,11 @@ <h3 class="callout-title">Practice Accumulating<em>(continued)</em><a class="anc
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="co"># List of word lengths: ["red", "green", "blue"] =&gt; [3, 5, 4]</span></span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a>lengths <span class="op">=</span> ____</span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb21-4"><a href="#cb21-4" aria-hidden="true" tabindex="-1"></a>    lengths.____(____)</span>
-<span id="cb21-5"><a href="#cb21-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a><span class="co"># List of word lengths: ["red", "green", "blue"] =&gt; [3, 5, 4]</span></span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a>lengths <span class="op">=</span> ____</span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb21-4"><a href="#cb21-4" tabindex="-1"></a>    lengths.____(____)</span>
+<span id="cb21-5"><a href="#cb21-5" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7012,15 +7013,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>lengths <span class="op">=</span> []</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb22-3"><a href="#cb22-3" aria-hidden="true" tabindex="-1"></a>    lengths.append(<span class="bu">len</span>(word))</span>
-<span id="cb22-4"><a href="#cb22-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>lengths <span class="op">=</span> []</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb22-3"><a href="#cb22-3" tabindex="-1"></a>    lengths.append(<span class="bu">len</span>(word))</span>
+<span id="cb22-4"><a href="#cb22-4" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7037,12 +7038,12 @@ <h3 class="callout-title">Practice Accumulating<em>(continued)</em><a class="anc
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Concatenate all words: ["red", "green", "blue"] =&gt; "redgreenblue"</span></span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
-<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> ____</span>
-<span id="cb23-4"><a href="#cb23-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> ____ <span class="kw">in</span> ____:</span>
-<span id="cb23-5"><a href="#cb23-5" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb23-6"><a href="#cb23-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="co"># Concatenate all words: ["red", "green", "blue"] =&gt; "redgreenblue"</span></span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
+<span id="cb23-3"><a href="#cb23-3" tabindex="-1"></a>result <span class="op">=</span> ____</span>
+<span id="cb23-4"><a href="#cb23-4" tabindex="-1"></a><span class="cf">for</span> ____ <span class="kw">in</span> ____:</span>
+<span id="cb23-5"><a href="#cb23-5" tabindex="-1"></a>    ____</span>
+<span id="cb23-6"><a href="#cb23-6" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7052,16 +7053,16 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Show me the solution</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> words:</span>
-<span id="cb24-4"><a href="#cb24-4" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> result <span class="op">+</span> word</span>
-<span id="cb24-5"><a href="#cb24-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb24-3"><a href="#cb24-3" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> words:</span>
+<span id="cb24-4"><a href="#cb24-4" tabindex="-1"></a>    result <span class="op">=</span> result <span class="op">+</span> word</span>
+<span id="cb24-5"><a href="#cb24-5" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7088,15 +7089,15 @@ <h3 class="callout-title">Practice Accumulating<em>(continued)</em><a class="anc
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a>acronym <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a>    acronym <span class="op">=</span> acronym <span class="op">+</span> word[<span class="dv">0</span>].upper()</span>
-<span id="cb25-4"><a href="#cb25-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(acronym)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a>acronym <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a>    acronym <span class="op">=</span> acronym <span class="op">+</span> word[<span class="dv">0</span>].upper()</span>
+<span id="cb25-4"><a href="#cb25-4" tabindex="-1"></a><span class="bu">print</span>(acronym)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7116,13 +7117,13 @@ <h3 class="callout-title">Cumulative Sum<a class="anchor" aria-label="anchor" hr
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>cumulative.append(total)</span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
-<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> total <span class="op">+</span> number</span>
-<span id="cb26-5"><a href="#cb26-5" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb26-6"><a href="#cb26-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span>
-<span id="cb26-7"><a href="#cb26-7" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>cumulative.append(total)</span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
+<span id="cb26-4"><a href="#cb26-4" tabindex="-1"></a>total <span class="op">=</span> total <span class="op">+</span> number</span>
+<span id="cb26-5"><a href="#cb26-5" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb26-6"><a href="#cb26-6" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span>
+<span id="cb26-7"><a href="#cb26-7" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -7132,18 +7133,18 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Show me the solution</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span>
-<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
-<span id="cb27-4"><a href="#cb27-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
-<span id="cb27-5"><a href="#cb27-5" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> number</span>
-<span id="cb27-6"><a href="#cb27-6" aria-hidden="true" tabindex="-1"></a>    cumulative.append(total)</span>
-<span id="cb27-7"><a href="#cb27-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span>
+<span id="cb27-3"><a href="#cb27-3" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
+<span id="cb27-4"><a href="#cb27-4" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
+<span id="cb27-5"><a href="#cb27-5" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> number</span>
+<span id="cb27-6"><a href="#cb27-6" tabindex="-1"></a>    cumulative.append(total)</span>
+<span id="cb27-7"><a href="#cb27-7" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7170,13 +7171,13 @@ <h3 class="callout-title">Identifying Variable Name Errors<a class="anchor" aria
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
-<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> (Number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb28-4"><a href="#cb28-4" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> a</span>
-<span id="cb28-5"><a href="#cb28-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb28-6"><a href="#cb28-6" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
-<span id="cb28-7"><a href="#cb28-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
+<span id="cb28-3"><a href="#cb28-3" tabindex="-1"></a>    <span class="cf">if</span> (Number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb28-4"><a href="#cb28-4" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> a</span>
+<span id="cb28-5"><a href="#cb28-5" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb28-6"><a href="#cb28-6" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
+<span id="cb28-7"><a href="#cb28-7" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7186,7 +7187,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution9" aria-expanded="false" aria-controls="collapseSolution9">
   <h4 class="accordion-header" id="headingSolution9">Show me the solution</h4>
 </button>
-<div id="collapseSolution9" class="accordion-collapse collapse" data-bs-parent="#accordionSolution9" aria-labelledby="headingSolution9">
+<div id="collapseSolution9" class="accordion-collapse collapse" aria-labelledby="headingSolution9" data-bs-parent="#accordionSolution9">
 <div class="accordion-body">
 <ul>
 <li>Python variable names are case sensitive: <code>number</code> and
@@ -7199,14 +7200,14 @@ <h4 class="accordion-header" id="headingSolution9">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb29">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a>message <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
-<span id="cb29-4"><a href="#cb29-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> (number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb29-5"><a href="#cb29-5" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"a"</span></span>
-<span id="cb29-6"><a href="#cb29-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb29-7"><a href="#cb29-7" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
-<span id="cb29-8"><a href="#cb29-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" tabindex="-1"></a>message <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb29-2"><a href="#cb29-2" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb29-3"><a href="#cb29-3" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
+<span id="cb29-4"><a href="#cb29-4" tabindex="-1"></a>    <span class="cf">if</span> (number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb29-5"><a href="#cb29-5" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"a"</span></span>
+<span id="cb29-6"><a href="#cb29-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb29-7"><a href="#cb29-7" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
+<span id="cb29-8"><a href="#cb29-8" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7230,8 +7231,8 @@ <h3 class="callout-title">Identifying Item Errors<a class="anchor" aria-label="a
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
-<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">4</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
+<span id="cb30-2"><a href="#cb30-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">4</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -7241,15 +7242,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution10" aria-expanded="false" aria-controls="collapseSolution10">
   <h4 class="accordion-header" id="headingSolution10">Show me the solution</h4>
 </button>
-<div id="collapseSolution10" class="accordion-collapse collapse" data-bs-parent="#accordionSolution10" aria-labelledby="headingSolution10">
+<div id="collapseSolution10" class="accordion-collapse collapse" aria-labelledby="headingSolution10" data-bs-parent="#accordionSolution10">
 <div class="accordion-body">
 <p>This list has 4 elements and the index to access the last element in
 the list is <code>3</code>.</p>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">3</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -7335,13 +7336,13 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">3.54</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(mass, <span class="st">'is large'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">2.07</span></span>
-<span id="cb1-6"><a href="#cb1-6" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb1-7"><a href="#cb1-7" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span> (mass, <span class="st">'is large'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">3.54</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    <span class="bu">print</span>(mass, <span class="st">'is large'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a></span>
+<span id="cb1-5"><a href="#cb1-5" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">2.07</span></span>
+<span id="cb1-6"><a href="#cb1-6" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb1-7"><a href="#cb1-7" tabindex="-1"></a>    <span class="bu">print</span> (mass, <span class="st">'is large'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7359,10 +7360,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
-<span id="cb3-3"><a href="#cb3-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb3-4"><a href="#cb3-4" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
+<span id="cb3-3"><a href="#cb3-3" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb3-4"><a href="#cb3-4" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7383,12 +7384,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb5-6"><a href="#cb5-6" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7414,14 +7415,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">9.0</span>:</span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is HUGE'</span>)</span>
-<span id="cb7-5"><a href="#cb7-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb7-6"><a href="#cb7-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
-<span id="cb7-7"><a href="#cb7-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb7-8"><a href="#cb7-8" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">9.0</span>:</span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is HUGE'</span>)</span>
+<span id="cb7-5"><a href="#cb7-5" tabindex="-1"></a>    <span class="cf">elif</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb7-6"><a href="#cb7-6" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
+<span id="cb7-7"><a href="#cb7-7" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb7-8"><a href="#cb7-8" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7443,13 +7444,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>grade <span class="op">=</span> <span class="dv">85</span></span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> grade <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is A'</span>)</span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">80</span>:</span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is B'</span>)</span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is C'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>grade <span class="op">=</span> <span class="dv">85</span></span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="cf">if</span> grade <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is A'</span>)</span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">80</span>:</span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is B'</span>)</span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is C'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7463,12 +7464,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
-<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a><span class="cf">else</span>:</span>
-<span id="cb11-5"><a href="#cb11-5" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'adjusting velocity'</span>)</span>
-<span id="cb11-6"><a href="#cb11-6" aria-hidden="true" tabindex="-1"></a>    velocity <span class="op">=</span> <span class="fl">50.0</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
+<span id="cb11-4"><a href="#cb11-4" tabindex="-1"></a><span class="cf">else</span>:</span>
+<span id="cb11-5"><a href="#cb11-5" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'adjusting velocity'</span>)</span>
+<span id="cb11-6"><a href="#cb11-6" tabindex="-1"></a>    velocity <span class="op">=</span> <span class="fl">50.0</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7482,16 +7483,16 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>): <span class="co"># execute the loop 5 times</span></span>
-<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(i, <span class="st">':'</span>, velocity)</span>
-<span id="cb13-4"><a href="#cb13-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
-<span id="cb13-5"><a href="#cb13-5" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
-<span id="cb13-6"><a href="#cb13-6" aria-hidden="true" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">-</span> <span class="fl">5.0</span></span>
-<span id="cb13-7"><a href="#cb13-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb13-8"><a href="#cb13-8" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too slow'</span>)</span>
-<span id="cb13-9"><a href="#cb13-9" aria-hidden="true" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">+</span> <span class="fl">10.0</span></span>
-<span id="cb13-10"><a href="#cb13-10" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'final velocity:'</span>, velocity)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>): <span class="co"># execute the loop 5 times</span></span>
+<span id="cb13-3"><a href="#cb13-3" tabindex="-1"></a>    <span class="bu">print</span>(i, <span class="st">':'</span>, velocity)</span>
+<span id="cb13-4"><a href="#cb13-4" tabindex="-1"></a>    <span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
+<span id="cb13-5"><a href="#cb13-5" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
+<span id="cb13-6"><a href="#cb13-6" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">-</span> <span class="fl">5.0</span></span>
+<span id="cb13-7"><a href="#cb13-7" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb13-8"><a href="#cb13-8" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too slow'</span>)</span>
+<span id="cb13-9"><a href="#cb13-9" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">+</span> <span class="fl">10.0</span></span>
+<span id="cb13-10"><a href="#cb13-10" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'final velocity:'</span>, velocity)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7590,12 +7591,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <code>velocity</code>, since its value is updated by the last iteration
 of the loop.</li>
 </ul>
-<div id="compound-relations-using-and-or-and-parentheses" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="compound-relations-using-and-or-and-parentheses" class="callout-inner">
-<h3 class="callout-title">Compound Relations Using<code>and</code>,<code>or</code>, and Parentheses<a class="anchor" aria-label="anchor" href="#compound-relations-using-and-or-and-parentheses"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="compound-relations-using-and-or-and-parentheses">Compound Relations Using <code>and</code>,
+<code>or</code>, and Parentheses<a class="anchor" aria-label="anchor" href="#compound-relations-using-and-or-and-parentheses"></a>
 </h3>
 <div class="callout-content">
 <p>Often, you want some combination of things to be true. You can
@@ -7604,19 +7606,19 @@ <h3 class="callout-title">Compound Relations Using<code>and</code>,<code>or</cod
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>mass     <span class="op">=</span> [ <span class="fl">3.54</span>,  <span class="fl">2.07</span>,  <span class="fl">9.22</span>,  <span class="fl">1.86</span>,  <span class="fl">1.71</span>]</span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>velocity <span class="op">=</span> [<span class="fl">10.00</span>, <span class="fl">20.00</span>, <span class="fl">30.00</span>, <span class="fl">25.00</span>, <span class="fl">20.00</span>]</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>):</span>
-<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> mass[i] <span class="op">&gt;</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
-<span id="cb15-7"><a href="#cb15-7" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Fast heavy object.  Duck!"</span>)</span>
-<span id="cb15-8"><a href="#cb15-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&gt;</span> <span class="dv">2</span> <span class="kw">and</span> mass[i] <span class="op">&lt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
-<span id="cb15-9"><a href="#cb15-9" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Normal traffic"</span>)</span>
-<span id="cb15-10"><a href="#cb15-10" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
-<span id="cb15-11"><a href="#cb15-11" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Slow light object.  Ignore it"</span>)</span>
-<span id="cb15-12"><a href="#cb15-12" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb15-13"><a href="#cb15-13" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Whoa!  Something is up with the data.  Check it"</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a>mass     <span class="op">=</span> [ <span class="fl">3.54</span>,  <span class="fl">2.07</span>,  <span class="fl">9.22</span>,  <span class="fl">1.86</span>,  <span class="fl">1.71</span>]</span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>velocity <span class="op">=</span> [<span class="fl">10.00</span>, <span class="fl">20.00</span>, <span class="fl">30.00</span>, <span class="fl">25.00</span>, <span class="fl">20.00</span>]</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a></span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb15-5"><a href="#cb15-5" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>):</span>
+<span id="cb15-6"><a href="#cb15-6" tabindex="-1"></a>    <span class="cf">if</span> mass[i] <span class="op">&gt;</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
+<span id="cb15-7"><a href="#cb15-7" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Fast heavy object.  Duck!"</span>)</span>
+<span id="cb15-8"><a href="#cb15-8" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&gt;</span> <span class="dv">2</span> <span class="kw">and</span> mass[i] <span class="op">&lt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
+<span id="cb15-9"><a href="#cb15-9" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Normal traffic"</span>)</span>
+<span id="cb15-10"><a href="#cb15-10" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
+<span id="cb15-11"><a href="#cb15-11" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Slow light object.  Ignore it"</span>)</span>
+<span id="cb15-12"><a href="#cb15-12" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb15-13"><a href="#cb15-13" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Whoa!  Something is up with the data.  Check it"</span>)</span></code></pre>
 </div>
 <p>Just like with arithmetic, you can and should use parentheses
 whenever there is possible ambiguity. A good general rule is to
@@ -7625,14 +7627,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span></code></pre>
 </div>
 <p>write one of these:</p>
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> (mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span>) <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> (mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>):</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="cf">if</span> (mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span>) <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> (mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>):</span></code></pre>
 </div>
 <p>so it is perfectly clear to a reader (and to Python) what you really
 mean.</p>
@@ -7651,12 +7653,12 @@ <h3 class="callout-title">Tracing Execution<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">71.9</span></span>
-<span id="cb18-2"><a href="#cb18-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> pressure <span class="op">&gt;</span> <span class="fl">50.0</span>:</span>
-<span id="cb18-3"><a href="#cb18-3" aria-hidden="true" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">25.0</span></span>
-<span id="cb18-4"><a href="#cb18-4" aria-hidden="true" tabindex="-1"></a><span class="cf">elif</span> pressure <span class="op">&lt;=</span> <span class="fl">50.0</span>:</span>
-<span id="cb18-5"><a href="#cb18-5" aria-hidden="true" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">0.0</span></span>
-<span id="cb18-6"><a href="#cb18-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(pressure)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">71.9</span></span>
+<span id="cb18-2"><a href="#cb18-2" tabindex="-1"></a><span class="cf">if</span> pressure <span class="op">&gt;</span> <span class="fl">50.0</span>:</span>
+<span id="cb18-3"><a href="#cb18-3" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">25.0</span></span>
+<span id="cb18-4"><a href="#cb18-4" tabindex="-1"></a><span class="cf">elif</span> pressure <span class="op">&lt;=</span> <span class="fl">50.0</span>:</span>
+<span id="cb18-5"><a href="#cb18-5" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">0.0</span></span>
+<span id="cb18-6"><a href="#cb18-6" tabindex="-1"></a><span class="bu">print</span>(pressure)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7691,14 +7693,14 @@ <h3 class="callout-title">Trimming Values<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> ____</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
-<span id="cb20-4"><a href="#cb20-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
-<span id="cb20-5"><a href="#cb20-5" aria-hidden="true" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
-<span id="cb20-6"><a href="#cb20-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb20-7"><a href="#cb20-7" aria-hidden="true" tabindex="-1"></a>        ____</span>
-<span id="cb20-8"><a href="#cb20-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>result <span class="op">=</span> ____</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
+<span id="cb20-4"><a href="#cb20-4" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
+<span id="cb20-5"><a href="#cb20-5" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
+<span id="cb20-6"><a href="#cb20-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb20-7"><a href="#cb20-7" tabindex="-1"></a>        ____</span>
+<span id="cb20-8"><a href="#cb20-8" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7718,14 +7720,14 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> []</span>
-<span id="cb22-3"><a href="#cb22-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
-<span id="cb22-4"><a href="#cb22-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> value <span class="op">&lt;</span> <span class="fl">0.0</span>:</span>
-<span id="cb22-5"><a href="#cb22-5" aria-hidden="true" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
-<span id="cb22-6"><a href="#cb22-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb22-7"><a href="#cb22-7" aria-hidden="true" tabindex="-1"></a>        result.append(<span class="dv">1</span>)</span>
-<span id="cb22-8"><a href="#cb22-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>result <span class="op">=</span> []</span>
+<span id="cb22-3"><a href="#cb22-3" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
+<span id="cb22-4"><a href="#cb22-4" tabindex="-1"></a>    <span class="cf">if</span> value <span class="op">&lt;</span> <span class="fl">0.0</span>:</span>
+<span id="cb22-5"><a href="#cb22-5" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
+<span id="cb22-6"><a href="#cb22-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb22-7"><a href="#cb22-7" tabindex="-1"></a>        result.append(<span class="dv">1</span>)</span>
+<span id="cb22-8"><a href="#cb22-8" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7744,12 +7746,12 @@ <h3 class="callout-title">Processing Small Files<a class="anchor" aria-label="an
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb23-4"><a href="#cb23-4" aria-hidden="true" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb23-5"><a href="#cb23-5" aria-hidden="true" tabindex="-1"></a>    ____:</span>
-<span id="cb23-6"><a href="#cb23-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb23-3"><a href="#cb23-3" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb23-4"><a href="#cb23-4" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb23-5"><a href="#cb23-5" tabindex="-1"></a>    ____:</span>
+<span id="cb23-6"><a href="#cb23-6" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
 </div>
 </div>
 </div>
@@ -7764,12 +7766,12 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb24-4"><a href="#cb24-4" aria-hidden="true" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb24-5"><a href="#cb24-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(contents) <span class="op">&lt;</span> <span class="dv">50</span>:</span>
-<span id="cb24-6"><a href="#cb24-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb24-3"><a href="#cb24-3" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb24-4"><a href="#cb24-4" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb24-5"><a href="#cb24-5" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(contents) <span class="op">&lt;</span> <span class="dv">50</span>:</span>
+<span id="cb24-6"><a href="#cb24-6" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
 </div>
 </div>
 </div>
@@ -7788,15 +7790,15 @@ <h3 class="callout-title">Initializing<a class="anchor" aria-label="anchor" href
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [...some test data...]</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb25-4"><a href="#cb25-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
-<span id="cb25-5"><a href="#cb25-5" aria-hidden="true" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
-<span id="cb25-6"><a href="#cb25-6" aria-hidden="true" tabindex="-1"></a>    ____:</span>
-<span id="cb25-7"><a href="#cb25-7" aria-hidden="true" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(____, v)</span>
-<span id="cb25-8"><a href="#cb25-8" aria-hidden="true" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(____, v)</span>
-<span id="cb25-9"><a href="#cb25-9" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a>values <span class="op">=</span> [...some test data...]</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb25-4"><a href="#cb25-4" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
+<span id="cb25-5"><a href="#cb25-5" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
+<span id="cb25-6"><a href="#cb25-6" tabindex="-1"></a>    ____:</span>
+<span id="cb25-7"><a href="#cb25-7" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(____, v)</span>
+<span id="cb25-8"><a href="#cb25-8" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(____, v)</span>
+<span id="cb25-9"><a href="#cb25-9" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 <p>What are the advantages and disadvantages of using this method to
 find the range of the data?</p>
@@ -7813,15 +7815,15 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">and</span> largest <span class="kw">is</span> <span class="va">None</span>:</span>
-<span id="cb26-5"><a href="#cb26-5" aria-hidden="true" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
-<span id="cb26-6"><a href="#cb26-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb26-7"><a href="#cb26-7" aria-hidden="true" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(smallest, v)</span>
-<span id="cb26-8"><a href="#cb26-8" aria-hidden="true" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(largest, v)</span>
-<span id="cb26-9"><a href="#cb26-9" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb26-4"><a href="#cb26-4" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">and</span> largest <span class="kw">is</span> <span class="va">None</span>:</span>
+<span id="cb26-5"><a href="#cb26-5" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
+<span id="cb26-6"><a href="#cb26-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb26-7"><a href="#cb26-7" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(smallest, v)</span>
+<span id="cb26-8"><a href="#cb26-8" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(largest, v)</span>
+<span id="cb26-9"><a href="#cb26-9" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 <p>If you wrote <code>== None</code> instead of <code>is None</code>,
 that works too, but Python programmers always write <code>is None</code>
@@ -7835,14 +7837,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
-<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb27-4"><a href="#cb27-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&lt;</span> smallest:</span>
-<span id="cb27-5"><a href="#cb27-5" aria-hidden="true" tabindex="-1"></a>        smallest <span class="op">=</span> v</span>
-<span id="cb27-6"><a href="#cb27-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> largest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&gt;</span> largest:</span>
-<span id="cb27-7"><a href="#cb27-7" aria-hidden="true" tabindex="-1"></a>        largest <span class="op">=</span> v</span>
-<span id="cb27-8"><a href="#cb27-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
+<span id="cb27-3"><a href="#cb27-3" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb27-4"><a href="#cb27-4" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&lt;</span> smallest:</span>
+<span id="cb27-5"><a href="#cb27-5" tabindex="-1"></a>        smallest <span class="op">=</span> v</span>
+<span id="cb27-6"><a href="#cb27-6" tabindex="-1"></a>    <span class="cf">if</span> largest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&gt;</span> largest:</span>
+<span id="cb27-7"><a href="#cb27-7" tabindex="-1"></a>        largest <span class="op">=</span> v</span>
+<span id="cb27-8"><a href="#cb27-8" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 <p>Now we have one loop, but four comparison tests. There are two ways
 we could improve it further: either use fewer comparisons in each
@@ -7851,10 +7853,10 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a>smallest <span class="op">=</span> <span class="bu">min</span>(values)</span>
-<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a>largest <span class="op">=</span> <span class="bu">max</span>(values)</span>
-<span id="cb28-4"><a href="#cb28-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a>smallest <span class="op">=</span> <span class="bu">min</span>(values)</span>
+<span id="cb28-3"><a href="#cb28-3" tabindex="-1"></a>largest <span class="op">=</span> <span class="bu">max</span>(values)</span>
+<span id="cb28-4"><a href="#cb28-4" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7930,10 +7932,10 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> [<span class="st">'data/gapminder_gdp_africa.csv'</span>, <span class="st">'data/gapminder_gdp_asia.csv'</span>]:</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(filename, data.<span class="bu">min</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> [<span class="st">'data/gapminder_gdp_africa.csv'</span>, <span class="st">'data/gapminder_gdp_asia.csv'</span>]:</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    <span class="bu">print</span>(filename, data.<span class="bu">min</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7984,8 +7986,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all csv files in data directory:'</span>, glob.glob(<span class="st">'data/*.csv'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all csv files in data directory:'</span>, glob.glob(<span class="st">'data/*.csv'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7997,7 +7999,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all PDB files:'</span>, glob.glob(<span class="st">'*.pdb'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all PDB files:'</span>, glob.glob(<span class="st">'*.pdb'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8015,9 +8017,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_*.csv'</span>):</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(filename, data[<span class="st">'gdpPercap_1952'</span>].<span class="bu">min</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_*.csv'</span>):</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a>    <span class="bu">print</span>(filename, data[<span class="st">'gdpPercap_1952'</span>].<span class="bu">min</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8059,7 +8061,7 @@ <h3 class="callout-title">Determining Matches<a class="anchor" aria-label="ancho
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>1 is not matched by the glob.</p>
 </div>
@@ -8079,13 +8081,13 @@ <h3 class="callout-title">Minimum File Size<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a>fewest <span class="op">=</span> ____</span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.____(filename)</span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(____, dataframe.shape[<span class="dv">0</span>])</span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a>fewest <span class="op">=</span> ____</span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.____(filename)</span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(____, dataframe.shape[<span class="dv">0</span>])</span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
 </div>
 <p>Note that the <a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.shape.html" class="external-link"><code>DataFrame.shape()</code>
 method</a> returns a tuple with the number of rows and columns of the
@@ -8098,18 +8100,18 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>fewest <span class="op">=</span> <span class="bu">float</span>(<span class="st">'Inf'</span>)</span>
-<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb10-5"><a href="#cb10-5" aria-hidden="true" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb10-6"><a href="#cb10-6" aria-hidden="true" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(fewest, dataframe.shape[<span class="dv">0</span>])</span>
-<span id="cb10-7"><a href="#cb10-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb10-3"><a href="#cb10-3" tabindex="-1"></a>fewest <span class="op">=</span> <span class="bu">float</span>(<span class="st">'Inf'</span>)</span>
+<span id="cb10-4"><a href="#cb10-4" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb10-5"><a href="#cb10-5" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb10-6"><a href="#cb10-6" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(fewest, dataframe.shape[<span class="dv">0</span>])</span>
+<span id="cb10-7"><a href="#cb10-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
 </div>
 <p>You might have chosen to initialize the <code>fewest</code> variable
 with a number greater than the numbers you’re dealing with, but that
@@ -8139,7 +8141,7 @@ <h3 class="callout-title">Comparing Data<a class="anchor" aria-label="anchor" hr
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>This solution builds a useful legend by using the <a href="https://docs.python.org/3/library/stdtypes.html#str.split" class="external-link">string
 <code>split</code> method</a> to extract the <code>region</code> from
@@ -8147,31 +8149,31 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span>
-<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a>fig, ax <span class="op">=</span> plt.subplots(<span class="dv">1</span>,<span class="dv">1</span>)</span>
-<span id="cb11-5"><a href="#cb11-5" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_gdp*.csv'</span>):</span>
-<span id="cb11-6"><a href="#cb11-6" aria-hidden="true" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb11-7"><a href="#cb11-7" aria-hidden="true" tabindex="-1"></a>    <span class="co"># extract &lt;region&gt; from the filename, expected to be in the format 'data/gapminder_gdp_&lt;region&gt;.csv'.</span></span>
-<span id="cb11-8"><a href="#cb11-8" aria-hidden="true" tabindex="-1"></a>    <span class="co"># we will split the string using the split method and `_` as our separator,</span></span>
-<span id="cb11-9"><a href="#cb11-9" aria-hidden="true" tabindex="-1"></a>    <span class="co"># retrieve the last string in the list that split returns (`&lt;region&gt;.csv`), </span></span>
-<span id="cb11-10"><a href="#cb11-10" aria-hidden="true" tabindex="-1"></a>    <span class="co"># and then remove the `.csv` extension from that string.</span></span>
-<span id="cb11-11"><a href="#cb11-11" aria-hidden="true" tabindex="-1"></a>    region <span class="op">=</span> filename.split(<span class="st">'_'</span>)[<span class="op">-</span><span class="dv">1</span>][:<span class="op">-</span><span class="dv">4</span>] </span>
-<span id="cb11-12"><a href="#cb11-12" aria-hidden="true" tabindex="-1"></a>    dataframe.mean().plot(ax<span class="op">=</span>ax, label<span class="op">=</span>region)</span>
-<span id="cb11-13"><a href="#cb11-13" aria-hidden="true" tabindex="-1"></a>plt.legend()</span>
-<span id="cb11-14"><a href="#cb11-14" aria-hidden="true" tabindex="-1"></a>plt.show()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span>
+<span id="cb11-4"><a href="#cb11-4" tabindex="-1"></a>fig, ax <span class="op">=</span> plt.subplots(<span class="dv">1</span>,<span class="dv">1</span>)</span>
+<span id="cb11-5"><a href="#cb11-5" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_gdp*.csv'</span>):</span>
+<span id="cb11-6"><a href="#cb11-6" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb11-7"><a href="#cb11-7" tabindex="-1"></a>    <span class="co"># extract &lt;region&gt; from the filename, expected to be in the format 'data/gapminder_gdp_&lt;region&gt;.csv'.</span></span>
+<span id="cb11-8"><a href="#cb11-8" tabindex="-1"></a>    <span class="co"># we will split the string using the split method and `_` as our separator,</span></span>
+<span id="cb11-9"><a href="#cb11-9" tabindex="-1"></a>    <span class="co"># retrieve the last string in the list that split returns (`&lt;region&gt;.csv`), </span></span>
+<span id="cb11-10"><a href="#cb11-10" tabindex="-1"></a>    <span class="co"># and then remove the `.csv` extension from that string.</span></span>
+<span id="cb11-11"><a href="#cb11-11" tabindex="-1"></a>    region <span class="op">=</span> filename.split(<span class="st">'_'</span>)[<span class="op">-</span><span class="dv">1</span>][:<span class="op">-</span><span class="dv">4</span>] </span>
+<span id="cb11-12"><a href="#cb11-12" tabindex="-1"></a>    dataframe.mean().plot(ax<span class="op">=</span>ax, label<span class="op">=</span>region)</span>
+<span id="cb11-13"><a href="#cb11-13" tabindex="-1"></a>plt.legend()</span>
+<span id="cb11-14"><a href="#cb11-14" tabindex="-1"></a>plt.show()</span></code></pre>
 </div>
 </div>
 </div>
 </div>
 </div>
-<div id="dealing-with-file-paths" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="dealing-with-file-paths" class="callout-inner">
-<h3 class="callout-title">Dealing with File Paths<a class="anchor" aria-label="anchor" href="#dealing-with-file-paths"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="dealing-with-file-paths">Dealing with File Paths<a class="anchor" aria-label="anchor" href="#dealing-with-file-paths"></a>
 </h3>
 <div class="callout-content">
 <p>The <a href="https://docs.python.org/3/library/pathlib.html" class="external-link"><code>pathlib</code>
@@ -8183,10 +8185,10 @@ <h3 class="callout-title">Dealing with File Paths<a class="anchor" aria-label="a
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> pathlib <span class="im">import</span> Path</span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a>p <span class="op">=</span> Path(<span class="st">"data/gapminder_gdp_africa.csv"</span>)</span>
-<span id="cb12-4"><a href="#cb12-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(p.parent), <span class="bu">print</span>(p.stem), <span class="bu">print</span>(p.suffix)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="im">from</span> pathlib <span class="im">import</span> Path</span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a></span>
+<span id="cb12-3"><a href="#cb12-3" tabindex="-1"></a>p <span class="op">=</span> Path(<span class="st">"data/gapminder_gdp_africa.csv"</span>)</span>
+<span id="cb12-4"><a href="#cb12-4" tabindex="-1"></a><span class="bu">print</span>(p.parent), <span class="bu">print</span>(p.stem), <span class="bu">print</span>(p.suffix)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8328,10 +8330,10 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_greeting():</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Hello!'</span>)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'The weather is nice today.'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Right?'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="kw">def</span> print_greeting():</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Hello!'</span>)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'The weather is nice today.'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Right?'</span>)</span></code></pre>
 </div>
 </section><section id="defining-a-function-does-not-run-it."><h2 class="section-heading">Defining a function does not run it.<a class="anchor" aria-label="anchor" href="#defining-a-function-does-not-run-it."></a>
 </h2>
@@ -8347,7 +8349,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a>print_greeting()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a>print_greeting()</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8375,11 +8377,11 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-5"><a href="#cb4-5" aria-hidden="true" tabindex="-1"></a>print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
+<span id="cb4-3"><a href="#cb4-3" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span>
+<span id="cb4-4"><a href="#cb4-4" tabindex="-1"></a></span>
+<span id="cb4-5"><a href="#cb4-5" tabindex="-1"></a>print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8393,7 +8395,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>print_date(month<span class="op">=</span><span class="dv">3</span>, day<span class="op">=</span><span class="dv">19</span>, year<span class="op">=</span><span class="dv">1871</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a>print_date(month<span class="op">=</span><span class="dv">3</span>, day<span class="op">=</span><span class="dv">19</span>, year<span class="op">=</span><span class="dv">1871</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8422,16 +8424,16 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
-<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb8-3"><a href="#cb8-3" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
+<span id="cb8-4"><a href="#cb8-4" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">=</span> average([<span class="dv">1</span>, <span class="dv">3</span>, <span class="dv">4</span>])</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of actual values:'</span>, a)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>a <span class="op">=</span> average([<span class="dv">1</span>, <span class="dv">3</span>, <span class="dv">4</span>])</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of actual values:'</span>, a)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8441,7 +8443,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of empty list:'</span>, average([]))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of empty list:'</span>, average([]))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8457,8 +8459,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>result <span class="op">=</span> print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8485,10 +8487,10 @@ <h3 class="callout-title">Identifying Syntax Errors<a class="anchor" aria-label=
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> another_function</span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a>   <span class="bu">print</span>(<span class="st">"But at least python tells us about them!"</span>)</span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="kw">def</span> another_function</span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a>   <span class="bu">print</span>(<span class="st">"But at least python tells us about them!"</span>)</span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -8503,10 +8505,10 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> another_function():</span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"But at least Python tells us about them!"</span>)</span>
-<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a><span class="kw">def</span> another_function():</span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"But at least Python tells us about them!"</span>)</span>
+<span id="cb16-4"><a href="#cb16-4" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -8524,10 +8526,10 @@ <h3 class="callout-title">Definition and Use<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> report(pressure):</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'pressure is'</span>, pressure)</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'calling'</span>, report, <span class="fl">22.5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="kw">def</span> report(pressure):</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'pressure is'</span>, pressure)</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a></span>
+<span id="cb17-4"><a href="#cb17-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'calling'</span>, report, <span class="fl">22.5</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -8551,8 +8553,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"calling"</span>)</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>report(<span class="fl">22.5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"calling"</span>)</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>report(<span class="fl">22.5</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8578,11 +8580,11 @@ <h3 class="callout-title">Order of Operations<a class="anchor" aria-label="ancho
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_time(hour, minute, second):</span>
-<span id="cb21-4"><a href="#cb21-4" aria-hidden="true" tabindex="-1"></a>   time_string <span class="op">=</span> <span class="bu">str</span>(hour) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(minute) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(second)</span>
-<span id="cb21-5"><a href="#cb21-5" aria-hidden="true" tabindex="-1"></a>   <span class="bu">print</span>(time_string)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a></span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="kw">def</span> print_time(hour, minute, second):</span>
+<span id="cb21-4"><a href="#cb21-4" tabindex="-1"></a>   time_string <span class="op">=</span> <span class="bu">str</span>(hour) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(minute) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(second)</span>
+<span id="cb21-5"><a href="#cb21-5" tabindex="-1"></a>   <span class="bu">print</span>(time_string)</span></code></pre>
 </div>
 <ol start="2" style="list-style-type: decimal">
 <li>After fixing the problem above, explain why running this example
@@ -8591,8 +8593,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
 </div>
 <p>gives this output:</p>
 <div class="codewrapper">
@@ -8647,11 +8649,11 @@ <h3 class="callout-title">Encapsulation<a class="anchor" aria-label="anchor" hre
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> min_in_data(____):</span>
-<span id="cb24-4"><a href="#cb24-4" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> ____</span>
-<span id="cb24-5"><a href="#cb24-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> ____</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a></span>
+<span id="cb24-3"><a href="#cb24-3" tabindex="-1"></a><span class="kw">def</span> min_in_data(____):</span>
+<span id="cb24-4"><a href="#cb24-4" tabindex="-1"></a>    data <span class="op">=</span> ____</span>
+<span id="cb24-5"><a href="#cb24-5" tabindex="-1"></a>    <span class="cf">return</span> ____</span></code></pre>
 </div>
 </div>
 </div>
@@ -8666,11 +8668,11 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> min_in_data(filename):</span>
-<span id="cb25-4"><a href="#cb25-4" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb25-5"><a href="#cb25-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> data.<span class="bu">min</span>()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a></span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a><span class="kw">def</span> min_in_data(filename):</span>
+<span id="cb25-4"><a href="#cb25-4" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb25-5"><a href="#cb25-5" tabindex="-1"></a>    <span class="cf">return</span> data.<span class="bu">min</span>()</span></code></pre>
 </div>
 </div>
 </div>
@@ -8691,10 +8693,10 @@ <h3 class="callout-title">Find the First<a class="anchor" aria-label="anchor" hr
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> ____:</span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> ____:</span>
-<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a>            <span class="cf">return</span> ____</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> ____:</span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a>        <span class="cf">if</span> ____:</span>
+<span id="cb26-4"><a href="#cb26-4" tabindex="-1"></a>            <span class="cf">return</span> ____</span></code></pre>
 </div>
 </div>
 </div>
@@ -8709,18 +8711,18 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> v <span class="op">&lt;</span> <span class="dv">0</span>:</span>
-<span id="cb27-4"><a href="#cb27-4" aria-hidden="true" tabindex="-1"></a>            <span class="cf">return</span> v</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb27-3"><a href="#cb27-3" tabindex="-1"></a>        <span class="cf">if</span> v <span class="op">&lt;</span> <span class="dv">0</span>:</span>
+<span id="cb27-4"><a href="#cb27-4" tabindex="-1"></a>            <span class="cf">return</span> v</span></code></pre>
 </div>
 <p>If an empty list or a list with all positive values is passed to this
 function, it returns <code>None</code>:</p>
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>my_list <span class="op">=</span> []</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(first_negative(my_list))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>my_list <span class="op">=</span> []</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a><span class="bu">print</span>(first_negative(my_list))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8743,16 +8745,16 @@ <h3 class="callout-title">Calling by Name<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
-<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
-<span id="cb30-3"><a href="#cb30-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
+<span id="cb30-2"><a href="#cb30-2" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
+<span id="cb30-3"><a href="#cb30-3" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span></code></pre>
 </div>
 <p>We saw that we can call the function using <em>named arguments</em>,
 like this:</p>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>print_date(day<span class="op">=</span><span class="dv">1</span>, month<span class="op">=</span><span class="dv">2</span>, year<span class="op">=</span><span class="dv">2003</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>print_date(day<span class="op">=</span><span class="dv">1</span>, month<span class="op">=</span><span class="dv">2</span>, year<span class="op">=</span><span class="dv">2003</span>)</span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>What does <code>print_date(day=1, month=2, year=2003)</code>
@@ -8800,24 +8802,24 @@ <h3 class="callout-title">Encapsulation of an If/Print Block<a class="anchor" ar
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb32-2"><a href="#cb32-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb32-3"><a href="#cb32-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb32-4"><a href="#cb32-4" aria-hidden="true" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
-<span id="cb32-5"><a href="#cb32-5" aria-hidden="true" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
-<span id="cb32-6"><a href="#cb32-6" aria-hidden="true" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
-<span id="cb32-7"><a href="#cb32-7" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb32-8"><a href="#cb32-8" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(mass)</span>
-<span id="cb32-9"><a href="#cb32-9" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb32-10"><a href="#cb32-10" aria-hidden="true" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
-<span id="cb32-11"><a href="#cb32-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
-<span id="cb32-12"><a href="#cb32-12" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"jumbo"</span>)</span>
-<span id="cb32-13"><a href="#cb32-13" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
-<span id="cb32-14"><a href="#cb32-14" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"large"</span>)</span>
-<span id="cb32-15"><a href="#cb32-15" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
-<span id="cb32-16"><a href="#cb32-16" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"medium"</span>)</span>
-<span id="cb32-17"><a href="#cb32-17" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb32-18"><a href="#cb32-18" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"small"</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb32-2"><a href="#cb32-2" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb32-3"><a href="#cb32-3" tabindex="-1"></a></span>
+<span id="cb32-4"><a href="#cb32-4" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
+<span id="cb32-5"><a href="#cb32-5" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
+<span id="cb32-6"><a href="#cb32-6" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
+<span id="cb32-7"><a href="#cb32-7" tabindex="-1"></a></span>
+<span id="cb32-8"><a href="#cb32-8" tabindex="-1"></a>    <span class="bu">print</span>(mass)</span>
+<span id="cb32-9"><a href="#cb32-9" tabindex="-1"></a></span>
+<span id="cb32-10"><a href="#cb32-10" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
+<span id="cb32-11"><a href="#cb32-11" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
+<span id="cb32-12"><a href="#cb32-12" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"jumbo"</span>)</span>
+<span id="cb32-13"><a href="#cb32-13" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
+<span id="cb32-14"><a href="#cb32-14" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"large"</span>)</span>
+<span id="cb32-15"><a href="#cb32-15" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
+<span id="cb32-16"><a href="#cb32-16" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"medium"</span>)</span>
+<span id="cb32-17"><a href="#cb32-17" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb32-18"><a href="#cb32-18" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"small"</span>)</span></code></pre>
 </div>
 <p>The if-block that classifies the eggs might be useful in other
 situations, so to avoid repeating it, we could fold it into a function,
@@ -8826,15 +8828,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb33">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a><span class="co"># revised version</span></span>
-<span id="cb33-2"><a href="#cb33-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb33-3"><a href="#cb33-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb33-4"><a href="#cb33-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb33-5"><a href="#cb33-5" aria-hidden="true" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
-<span id="cb33-6"><a href="#cb33-6" aria-hidden="true" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
-<span id="cb33-7"><a href="#cb33-7" aria-hidden="true" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
-<span id="cb33-8"><a href="#cb33-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb33-9"><a href="#cb33-9" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(mass, get_egg_label(mass))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" tabindex="-1"></a><span class="co"># revised version</span></span>
+<span id="cb33-2"><a href="#cb33-2" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb33-3"><a href="#cb33-3" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb33-4"><a href="#cb33-4" tabindex="-1"></a></span>
+<span id="cb33-5"><a href="#cb33-5" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
+<span id="cb33-6"><a href="#cb33-6" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
+<span id="cb33-7"><a href="#cb33-7" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
+<span id="cb33-8"><a href="#cb33-8" tabindex="-1"></a></span>
+<span id="cb33-9"><a href="#cb33-9" tabindex="-1"></a>    <span class="bu">print</span>(mass, get_egg_label(mass))</span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>Create a function definition for <code>get_egg_label()</code> that
@@ -8861,22 +8863,22 @@ <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> get_egg_label(mass):</span>
-<span id="cb34-2"><a href="#cb34-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
-<span id="cb34-3"><a href="#cb34-3" aria-hidden="true" tabindex="-1"></a>    egg_label <span class="op">=</span> <span class="st">"Unlabelled"</span></span>
-<span id="cb34-4"><a href="#cb34-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
-<span id="cb34-5"><a href="#cb34-5" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"warning: egg might be dirty"</span></span>
-<span id="cb34-6"><a href="#cb34-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
-<span id="cb34-7"><a href="#cb34-7" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"jumbo"</span></span>
-<span id="cb34-8"><a href="#cb34-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
-<span id="cb34-9"><a href="#cb34-9" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"large"</span></span>
-<span id="cb34-10"><a href="#cb34-10" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
-<span id="cb34-11"><a href="#cb34-11" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"medium"</span></span>
-<span id="cb34-12"><a href="#cb34-12" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">50</span>:</span>
-<span id="cb34-13"><a href="#cb34-13" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"too light, probably spoiled"</span></span>
-<span id="cb34-14"><a href="#cb34-14" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb34-15"><a href="#cb34-15" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"small"</span></span>
-<span id="cb34-16"><a href="#cb34-16" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> egg_label</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a><span class="kw">def</span> get_egg_label(mass):</span>
+<span id="cb34-2"><a href="#cb34-2" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
+<span id="cb34-3"><a href="#cb34-3" tabindex="-1"></a>    egg_label <span class="op">=</span> <span class="st">"Unlabelled"</span></span>
+<span id="cb34-4"><a href="#cb34-4" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
+<span id="cb34-5"><a href="#cb34-5" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"warning: egg might be dirty"</span></span>
+<span id="cb34-6"><a href="#cb34-6" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
+<span id="cb34-7"><a href="#cb34-7" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"jumbo"</span></span>
+<span id="cb34-8"><a href="#cb34-8" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
+<span id="cb34-9"><a href="#cb34-9" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"large"</span></span>
+<span id="cb34-10"><a href="#cb34-10" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
+<span id="cb34-11"><a href="#cb34-11" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"medium"</span></span>
+<span id="cb34-12"><a href="#cb34-12" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">50</span>:</span>
+<span id="cb34-13"><a href="#cb34-13" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"too light, probably spoiled"</span></span>
+<span id="cb34-14"><a href="#cb34-14" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb34-15"><a href="#cb34-15" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"small"</span></span>
+<span id="cb34-16"><a href="#cb34-16" tabindex="-1"></a>    <span class="cf">return</span> egg_label</span></code></pre>
 </div>
 </div>
 </div>
@@ -8894,10 +8896,10 @@ <h3 class="callout-title">Encapsulating Data Analysis<a class="anchor" aria-labe
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb35-2"><a href="#cb35-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb35-3"><a href="#cb35-3" aria-hidden="true" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb35-4"><a href="#cb35-4" aria-hidden="true" tabindex="-1"></a>japan <span class="op">=</span> data_asia.loc[<span class="st">'Japan'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb35-2"><a href="#cb35-2" tabindex="-1"></a></span>
+<span id="cb35-3"><a href="#cb35-3" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb35-4"><a href="#cb35-4" tabindex="-1"></a>japan <span class="op">=</span> data_asia.loc[<span class="st">'Japan'</span>]</span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>Complete the statements below to obtain the average GDP for Japan
@@ -8906,9 +8908,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb36">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" aria-hidden="true" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
-<span id="cb36-2"><a href="#cb36-2" aria-hidden="true" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> ____)</span>
-<span id="cb36-3"><a href="#cb36-3" aria-hidden="true" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> ___] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> ___]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
+<span id="cb36-2"><a href="#cb36-2" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> ____)</span>
+<span id="cb36-3"><a href="#cb36-3" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> ___] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> ___]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
 </div>
 <ol start="2" style="list-style-type: decimal">
 <li>Abstract the code above into a single function.</li>
@@ -8916,12 +8918,12 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
-<span id="cb37-2"><a href="#cb37-2" aria-hidden="true" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span><span class="op">+</span>___<span class="op">+</span><span class="st">'.csv'</span>,delimiter<span class="op">=</span><span class="st">','</span>,index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb37-3"><a href="#cb37-3" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb37-4"><a href="#cb37-4" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb37-5"><a href="#cb37-5" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb37-6"><a href="#cb37-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
+<span id="cb37-2"><a href="#cb37-2" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span><span class="op">+</span>___<span class="op">+</span><span class="st">'.csv'</span>,delimiter<span class="op">=</span><span class="st">','</span>,index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb37-3"><a href="#cb37-3" tabindex="-1"></a>    ____</span>
+<span id="cb37-4"><a href="#cb37-4" tabindex="-1"></a>    ____</span>
+<span id="cb37-5"><a href="#cb37-5" tabindex="-1"></a>    ____</span>
+<span id="cb37-6"><a href="#cb37-6" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
 </div>
 <ol start="3" style="list-style-type: decimal">
 <li>How would you generalize this function if you did not know
@@ -8947,9 +8949,9 @@ <h4 class="accordion-header" id="headingSolution8">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb38">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
-<span id="cb38-2"><a href="#cb38-2" aria-hidden="true" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
-<span id="cb38-3"><a href="#cb38-3" aria-hidden="true" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
+<span id="cb38-2"><a href="#cb38-2" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
+<span id="cb38-3"><a href="#cb38-3" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
 </div>
 <ol start="2" style="list-style-type: decimal">
 <li>That code as a function is:</li>
@@ -8957,12 +8959,12 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb39">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
-<span id="cb39-2"><a href="#cb39-2" aria-hidden="true" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb39-3"><a href="#cb39-3" aria-hidden="true" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
-<span id="cb39-4"><a href="#cb39-4" aria-hidden="true" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
-<span id="cb39-5"><a href="#cb39-5" aria-hidden="true" tabindex="-1"></a>    avg <span class="op">=</span> (c.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> c.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>])<span class="op">/</span><span class="dv">2</span></span>
-<span id="cb39-6"><a href="#cb39-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
+<span id="cb39-2"><a href="#cb39-2" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb39-3"><a href="#cb39-3" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
+<span id="cb39-4"><a href="#cb39-4" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
+<span id="cb39-5"><a href="#cb39-5" tabindex="-1"></a>    avg <span class="op">=</span> (c.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> c.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>])<span class="op">/</span><span class="dv">2</span></span>
+<span id="cb39-6"><a href="#cb39-6" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
 </div>
 <ol start="3" style="list-style-type: decimal">
 <li>To obtain the average for the relevant years, we need to loop over
@@ -8971,23 +8973,23 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb40">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
-<span id="cb40-2"><a href="#cb40-2" aria-hidden="true" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb40-3"><a href="#cb40-3" aria-hidden="true" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
-<span id="cb40-4"><a href="#cb40-4" aria-hidden="true" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
-<span id="cb40-5"><a href="#cb40-5" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> <span class="fl">0.0</span></span>
-<span id="cb40-6"><a href="#cb40-6" aria-hidden="true" tabindex="-1"></a>    num_years <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb40-7"><a href="#cb40-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> yr_header <span class="kw">in</span> c.index: <span class="co"># c's index contains reported years</span></span>
-<span id="cb40-8"><a href="#cb40-8" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> yr_header.startswith(gdp_decade):</span>
-<span id="cb40-9"><a href="#cb40-9" aria-hidden="true" tabindex="-1"></a>            total <span class="op">=</span> total <span class="op">+</span> c.loc[yr_header]</span>
-<span id="cb40-10"><a href="#cb40-10" aria-hidden="true" tabindex="-1"></a>            num_years <span class="op">=</span> num_years <span class="op">+</span> <span class="dv">1</span></span>
-<span id="cb40-11"><a href="#cb40-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> total<span class="op">/</span>num_years</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
+<span id="cb40-2"><a href="#cb40-2" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb40-3"><a href="#cb40-3" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
+<span id="cb40-4"><a href="#cb40-4" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
+<span id="cb40-5"><a href="#cb40-5" tabindex="-1"></a>    total <span class="op">=</span> <span class="fl">0.0</span></span>
+<span id="cb40-6"><a href="#cb40-6" tabindex="-1"></a>    num_years <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb40-7"><a href="#cb40-7" tabindex="-1"></a>    <span class="cf">for</span> yr_header <span class="kw">in</span> c.index: <span class="co"># c's index contains reported years</span></span>
+<span id="cb40-8"><a href="#cb40-8" tabindex="-1"></a>        <span class="cf">if</span> yr_header.startswith(gdp_decade):</span>
+<span id="cb40-9"><a href="#cb40-9" tabindex="-1"></a>            total <span class="op">=</span> total <span class="op">+</span> c.loc[yr_header]</span>
+<span id="cb40-10"><a href="#cb40-10" tabindex="-1"></a>            num_years <span class="op">=</span> num_years <span class="op">+</span> <span class="dv">1</span></span>
+<span id="cb40-11"><a href="#cb40-11" tabindex="-1"></a>    <span class="cf">return</span> total<span class="op">/</span>num_years</span></code></pre>
 </div>
 <p>The function can now be called by:</p>
 <div class="codewrapper sourceCode" id="cb41">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" aria-hidden="true" tabindex="-1"></a>avg_gdp_in_decade(<span class="st">'Japan'</span>,<span class="st">'asia'</span>,<span class="dv">1983</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" tabindex="-1"></a>avg_gdp_in_decade(<span class="st">'Japan'</span>,<span class="st">'asia'</span>,<span class="dv">1983</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -9053,18 +9055,18 @@ <h4 class="accordion-header" id="headingSolution9">Show me the solution</h4>
 <li><div class="codewrapper sourceCode" id="cb43">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a>  <span class="kw">def</span> logistic_map(x, r):</span>
-<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a>      <span class="cf">return</span> r <span class="op">*</span> x <span class="op">*</span> (<span class="dv">1</span> <span class="op">-</span> x)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" tabindex="-1"></a>  <span class="kw">def</span> logistic_map(x, r):</span>
+<span id="cb43-2"><a href="#cb43-2" tabindex="-1"></a>      <span class="cf">return</span> r <span class="op">*</span> x <span class="op">*</span> (<span class="dv">1</span> <span class="op">-</span> x)</span></code></pre>
 </div></li>
 <li><div class="codewrapper sourceCode" id="cb44">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" aria-hidden="true" tabindex="-1"></a>  initial_population <span class="op">=</span> <span class="fl">0.5</span></span>
-<span id="cb44-2"><a href="#cb44-2" aria-hidden="true" tabindex="-1"></a>  t_final <span class="op">=</span> <span class="dv">10</span></span>
-<span id="cb44-3"><a href="#cb44-3" aria-hidden="true" tabindex="-1"></a>  r <span class="op">=</span> <span class="fl">1.0</span></span>
-<span id="cb44-4"><a href="#cb44-4" aria-hidden="true" tabindex="-1"></a>  population <span class="op">=</span> [initial_population]</span>
-<span id="cb44-5"><a href="#cb44-5" aria-hidden="true" tabindex="-1"></a>  <span class="cf">for</span> t <span class="kw">in</span> <span class="bu">range</span>(t_final):</span>
-<span id="cb44-6"><a href="#cb44-6" aria-hidden="true" tabindex="-1"></a>      population.append( logistic_map(population[t], r) )</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" tabindex="-1"></a>  initial_population <span class="op">=</span> <span class="fl">0.5</span></span>
+<span id="cb44-2"><a href="#cb44-2" tabindex="-1"></a>  t_final <span class="op">=</span> <span class="dv">10</span></span>
+<span id="cb44-3"><a href="#cb44-3" tabindex="-1"></a>  r <span class="op">=</span> <span class="fl">1.0</span></span>
+<span id="cb44-4"><a href="#cb44-4" tabindex="-1"></a>  population <span class="op">=</span> [initial_population]</span>
+<span id="cb44-5"><a href="#cb44-5" tabindex="-1"></a>  <span class="cf">for</span> t <span class="kw">in</span> <span class="bu">range</span>(t_final):</span>
+<span id="cb44-6"><a href="#cb44-6" tabindex="-1"></a>      population.append( logistic_map(population[t], r) )</span></code></pre>
 </div></li>
 <li>```python def iterate(initial_population, t_final, r): population =
 [initial_population] for t in range(t_final): population.append(
@@ -9084,12 +9086,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </div>
 </div>
 </div>
-<div id="using-functions-with-conditionals-in-pandas" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="using-functions-with-conditionals-in-pandas" class="callout-inner">
-<h3 class="callout-title">Using Functions With Conditionals in
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="using-functions-with-conditionals-in-pandas">Using Functions With Conditionals in
 Pandas<a class="anchor" aria-label="anchor" href="#using-functions-with-conditionals-in-pandas"></a>
 </h3>
 <div class="callout-content">
@@ -9099,24 +9101,24 @@ <h3 class="callout-title">Using Functions With Conditionals in
 <div class="codewrapper sourceCode" id="cb46">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> calculate_life_quartile(exp):</span>
-<span id="cb46-2"><a href="#cb46-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> exp <span class="op">&lt;</span> <span class="fl">58.41</span>:</span>
-<span id="cb46-3"><a href="#cb46-3" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the first quartile</span></span>
-<span id="cb46-4"><a href="#cb46-4" aria-hidden="true" tabindex="-1"></a>        <span class="cf">return</span> <span class="dv">1</span></span>
-<span id="cb46-5"><a href="#cb46-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">58.41</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">67.05</span>:</span>
-<span id="cb46-6"><a href="#cb46-6" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the second quartile</span></span>
-<span id="cb46-7"><a href="#cb46-7" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">2</span></span>
-<span id="cb46-8"><a href="#cb46-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">67.05</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">71.70</span>:</span>
-<span id="cb46-9"><a href="#cb46-9" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the third quartile</span></span>
-<span id="cb46-10"><a href="#cb46-10" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">3</span></span>
-<span id="cb46-11"><a href="#cb46-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">71.70</span>:</span>
-<span id="cb46-12"><a href="#cb46-12" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the fourth quartile</span></span>
-<span id="cb46-13"><a href="#cb46-13" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">4</span></span>
-<span id="cb46-14"><a href="#cb46-14" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb46-15"><a href="#cb46-15" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation has bad data</span></span>
-<span id="cb46-16"><a href="#cb46-16" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="va">None</span></span>
-<span id="cb46-17"><a href="#cb46-17" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb46-18"><a href="#cb46-18" aria-hidden="true" tabindex="-1"></a>calculate_life_quartile(<span class="fl">62.5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" tabindex="-1"></a><span class="kw">def</span> calculate_life_quartile(exp):</span>
+<span id="cb46-2"><a href="#cb46-2" tabindex="-1"></a>    <span class="cf">if</span> exp <span class="op">&lt;</span> <span class="fl">58.41</span>:</span>
+<span id="cb46-3"><a href="#cb46-3" tabindex="-1"></a>        <span class="co"># This observation is in the first quartile</span></span>
+<span id="cb46-4"><a href="#cb46-4" tabindex="-1"></a>        <span class="cf">return</span> <span class="dv">1</span></span>
+<span id="cb46-5"><a href="#cb46-5" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">58.41</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">67.05</span>:</span>
+<span id="cb46-6"><a href="#cb46-6" tabindex="-1"></a>        <span class="co"># This observation is in the second quartile</span></span>
+<span id="cb46-7"><a href="#cb46-7" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">2</span></span>
+<span id="cb46-8"><a href="#cb46-8" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">67.05</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">71.70</span>:</span>
+<span id="cb46-9"><a href="#cb46-9" tabindex="-1"></a>        <span class="co"># This observation is in the third quartile</span></span>
+<span id="cb46-10"><a href="#cb46-10" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">3</span></span>
+<span id="cb46-11"><a href="#cb46-11" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">71.70</span>:</span>
+<span id="cb46-12"><a href="#cb46-12" tabindex="-1"></a>        <span class="co"># This observation is in the fourth quartile</span></span>
+<span id="cb46-13"><a href="#cb46-13" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">4</span></span>
+<span id="cb46-14"><a href="#cb46-14" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb46-15"><a href="#cb46-15" tabindex="-1"></a>        <span class="co"># This observation has bad data</span></span>
+<span id="cb46-16"><a href="#cb46-16" tabindex="-1"></a>       <span class="cf">return</span> <span class="va">None</span></span>
+<span id="cb46-17"><a href="#cb46-17" tabindex="-1"></a></span>
+<span id="cb46-18"><a href="#cb46-18" tabindex="-1"></a>calculate_life_quartile(<span class="fl">62.5</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -9130,8 +9132,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb48">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>)</span>
-<span id="cb48-2"><a href="#cb48-2" aria-hidden="true" tabindex="-1"></a>data[<span class="st">'life_qrtl'</span>] <span class="op">=</span> data[<span class="st">'lifeExp_1952'</span>].<span class="bu">apply</span>(calculate_life_quartile)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>)</span>
+<span id="cb48-2"><a href="#cb48-2" tabindex="-1"></a>data[<span class="st">'life_qrtl'</span>] <span class="op">=</span> data[<span class="st">'lifeExp_1952'</span>].<span class="bu">apply</span>(calculate_life_quartile)</span></code></pre>
 </div>
 <p>There is a lot in that second line, so let’s take it piece by piece.
 On the right side of the <code>=</code> we start with
@@ -9219,11 +9221,11 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">103.9</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> adjust(t):</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    temperature <span class="op">=</span> t <span class="op">*</span> <span class="fl">1.43</span> <span class="op">/</span> pressure</span>
-<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> temperature</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">103.9</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="kw">def</span> adjust(t):</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    temperature <span class="op">=</span> t <span class="op">*</span> <span class="fl">1.43</span> <span class="op">/</span> pressure</span>
+<span id="cb1-5"><a href="#cb1-5" tabindex="-1"></a>    <span class="cf">return</span> temperature</span></code></pre>
 </div>
 <ul>
 <li>
@@ -9247,8 +9249,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'adjusted:'</span>, adjust(<span class="fl">0.9</span>))</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'temperature after call:'</span>, temperature)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'adjusted:'</span>, adjust(<span class="fl">0.9</span>))</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'temperature after call:'</span>, temperature)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -9276,13 +9278,13 @@ <h3 class="callout-title">Local and Global Variable Use<a class="anchor" aria-la
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>limit <span class="op">=</span> <span class="dv">100</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> clip(value):</span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">min</span>(<span class="bu">max</span>(<span class="fl">0.0</span>, value), limit)</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a>value <span class="op">=</span> <span class="op">-</span><span class="fl">22.5</span></span>
-<span id="cb5-7"><a href="#cb5-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(clip(value))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>limit <span class="op">=</span> <span class="dv">100</span></span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a></span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a><span class="kw">def</span> clip(value):</span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">min</span>(<span class="bu">max</span>(<span class="fl">0.0</span>, value), limit)</span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a></span>
+<span id="cb5-6"><a href="#cb5-6" tabindex="-1"></a>value <span class="op">=</span> <span class="op">-</span><span class="fl">22.5</span></span>
+<span id="cb5-7"><a href="#cb5-7" tabindex="-1"></a><span class="bu">print</span>(clip(value))</span></code></pre>
 </div>
 </div>
 </div>
@@ -9335,7 +9337,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <ol style="list-style-type: decimal">
 <li>Three levels.</li>
@@ -9458,10 +9460,10 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> calc_bulk_density(mass, volume):</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">'''Return dry bulk density = powder mass / powder volume.'''</span></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">assert</span> volume <span class="op">&gt;</span> <span class="dv">0</span></span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> mass <span class="op">/</span> volume</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="kw">def</span> calc_bulk_density(mass, volume):</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>    <span class="co">'''Return dry bulk density = powder mass / powder volume.'''</span></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    <span class="cf">assert</span> volume <span class="op">&gt;</span> <span class="dv">0</span></span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    <span class="cf">return</span> mass <span class="op">/</span> volume</span></code></pre>
 </div>
 <p>If the assertion is <code>False</code>, the Python interpreter raises
 an <code>AssertionError</code> runtime exception. The source code for
@@ -9480,14 +9482,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">"Return average of values, or None if no values are supplied."</span></span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
-<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span>
-<span id="cb2-7"><a href="#cb2-7" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb2-8"><a href="#cb2-8" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(average)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a>    <span class="co">"Return average of values, or None if no values are supplied."</span></span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a></span>
+<span id="cb2-4"><a href="#cb2-4" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb2-5"><a href="#cb2-5" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
+<span id="cb2-6"><a href="#cb2-6" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span>
+<span id="cb2-7"><a href="#cb2-7" tabindex="-1"></a></span>
+<span id="cb2-8"><a href="#cb2-8" tabindex="-1"></a><span class="bu">help</span>(average)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -9497,12 +9499,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 average(values)
     Return average of values, or None if no values are supplied.</code></pre>
 </div>
-<div id="multiline-strings" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="multiline-strings" class="callout-inner">
-<h3 class="callout-title">Multiline Strings<a class="anchor" aria-label="anchor" href="#multiline-strings"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="multiline-strings">Multiline Strings<a class="anchor" aria-label="anchor" href="#multiline-strings"></a>
 </h3>
 <div class="callout-content">
 <p>Often use <em>multiline strings</em> for documentation. These start
@@ -9511,10 +9513,10 @@ <h3 class="callout-title">Multiline Strings<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="co">"""This string spans</span></span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="co">multiple lines.</span></span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a><span class="co">Blank lines are allowed."""</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="co">"""This string spans</span></span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a><span class="co">multiple lines.</span></span>
+<span id="cb4-3"><a href="#cb4-3" tabindex="-1"></a></span>
+<span id="cb4-4"><a href="#cb4-4" tabindex="-1"></a><span class="co">Blank lines are allowed."""</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -9533,22 +9535,22 @@ <h3 class="callout-title">What Will Be Shown?<a class="anchor" aria-label="ancho
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="co">"Find maximum edit distance between multiple sequences."</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="co"># This finds the maximum distance between all sequences.</span></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> overall_max(sequences):</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>    <span class="co">'''Determine overall maximum edit distance.'''</span></span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-7"><a href="#cb5-7" aria-hidden="true" tabindex="-1"></a>    highest <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb5-8"><a href="#cb5-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> left <span class="kw">in</span> sequences:</span>
-<span id="cb5-9"><a href="#cb5-9" aria-hidden="true" tabindex="-1"></a>        <span class="cf">for</span> right <span class="kw">in</span> sequences:</span>
-<span id="cb5-10"><a href="#cb5-10" aria-hidden="true" tabindex="-1"></a>            <span class="co">'''Avoid checking sequence against itself.'''</span></span>
-<span id="cb5-11"><a href="#cb5-11" aria-hidden="true" tabindex="-1"></a>            <span class="cf">if</span> left <span class="op">!=</span> right:</span>
-<span id="cb5-12"><a href="#cb5-12" aria-hidden="true" tabindex="-1"></a>                this <span class="op">=</span> edit_distance(left, right)</span>
-<span id="cb5-13"><a href="#cb5-13" aria-hidden="true" tabindex="-1"></a>                highest <span class="op">=</span> <span class="bu">max</span>(highest, this)</span>
-<span id="cb5-14"><a href="#cb5-14" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-15"><a href="#cb5-15" aria-hidden="true" tabindex="-1"></a>    <span class="co"># Report.</span></span>
-<span id="cb5-16"><a href="#cb5-16" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> highest</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="co">"Find maximum edit distance between multiple sequences."</span></span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="co"># This finds the maximum distance between all sequences.</span></span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a></span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a><span class="kw">def</span> overall_max(sequences):</span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a>    <span class="co">'''Determine overall maximum edit distance.'''</span></span>
+<span id="cb5-6"><a href="#cb5-6" tabindex="-1"></a></span>
+<span id="cb5-7"><a href="#cb5-7" tabindex="-1"></a>    highest <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb5-8"><a href="#cb5-8" tabindex="-1"></a>    <span class="cf">for</span> left <span class="kw">in</span> sequences:</span>
+<span id="cb5-9"><a href="#cb5-9" tabindex="-1"></a>        <span class="cf">for</span> right <span class="kw">in</span> sequences:</span>
+<span id="cb5-10"><a href="#cb5-10" tabindex="-1"></a>            <span class="co">'''Avoid checking sequence against itself.'''</span></span>
+<span id="cb5-11"><a href="#cb5-11" tabindex="-1"></a>            <span class="cf">if</span> left <span class="op">!=</span> right:</span>
+<span id="cb5-12"><a href="#cb5-12" tabindex="-1"></a>                this <span class="op">=</span> edit_distance(left, right)</span>
+<span id="cb5-13"><a href="#cb5-13" tabindex="-1"></a>                highest <span class="op">=</span> <span class="bu">max</span>(highest, this)</span>
+<span id="cb5-14"><a href="#cb5-14" tabindex="-1"></a></span>
+<span id="cb5-15"><a href="#cb5-15" tabindex="-1"></a>    <span class="co"># Report.</span></span>
+<span id="cb5-16"><a href="#cb5-16" tabindex="-1"></a>    <span class="cf">return</span> highest</span></code></pre>
 </div>
 </div>
 </div>
@@ -9574,12 +9576,12 @@ <h3 class="callout-title">Document This<a class="anchor" aria-label="anchor" hre
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># Return the middle value of three.</span></span>
-<span id="cb6-3"><a href="#cb6-3" aria-hidden="true" tabindex="-1"></a>    <span class="co"># Assumes the values can actually be compared.</span></span>
-<span id="cb6-4"><a href="#cb6-4" aria-hidden="true" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
-<span id="cb6-5"><a href="#cb6-5" aria-hidden="true" tabindex="-1"></a>    values.sort()</span>
-<span id="cb6-6"><a href="#cb6-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
+<span id="cb6-2"><a href="#cb6-2" tabindex="-1"></a>    <span class="co"># Return the middle value of three.</span></span>
+<span id="cb6-3"><a href="#cb6-3" tabindex="-1"></a>    <span class="co"># Assumes the values can actually be compared.</span></span>
+<span id="cb6-4"><a href="#cb6-4" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
+<span id="cb6-5"><a href="#cb6-5" tabindex="-1"></a>    values.sort()</span>
+<span id="cb6-6"><a href="#cb6-6" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -9589,17 +9591,17 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">'''Return the middle value of three.</span></span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a><span class="co">    Assumes the values can actually be compared.'''</span></span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
-<span id="cb7-5"><a href="#cb7-5" aria-hidden="true" tabindex="-1"></a>    values.sort()</span>
-<span id="cb7-6"><a href="#cb7-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>    <span class="co">'''Return the middle value of three.</span></span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a><span class="co">    Assumes the values can actually be compared.'''</span></span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
+<span id="cb7-5"><a href="#cb7-5" tabindex="-1"></a>    values.sort()</span>
+<span id="cb7-6"><a href="#cb7-6" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -9624,21 +9626,21 @@ <h3 class="callout-title">Clean Up This Code<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a>n <span class="op">=</span> <span class="dv">10</span></span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>s <span class="op">=</span> <span class="st">'et cetera'</span></span>
-<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(s)</span>
-<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb8-5"><a href="#cb8-5" aria-hidden="true" tabindex="-1"></a><span class="cf">while</span> i <span class="op">&lt;</span> n:</span>
-<span id="cb8-6"><a href="#cb8-6" aria-hidden="true" tabindex="-1"></a>    <span class="co"># print('at', j)</span></span>
-<span id="cb8-7"><a href="#cb8-7" aria-hidden="true" tabindex="-1"></a>    new <span class="op">=</span> <span class="st">''</span></span>
-<span id="cb8-8"><a href="#cb8-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(<span class="bu">len</span>(s)):</span>
-<span id="cb8-9"><a href="#cb8-9" aria-hidden="true" tabindex="-1"></a>        left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
-<span id="cb8-10"><a href="#cb8-10" aria-hidden="true" tabindex="-1"></a>        right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>)<span class="op">%</span><span class="bu">len</span>(s)</span>
-<span id="cb8-11"><a href="#cb8-11" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> s[left]<span class="op">==</span>s[right]: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
-<span id="cb8-12"><a href="#cb8-12" aria-hidden="true" tabindex="-1"></a>        <span class="cf">else</span>: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
-<span id="cb8-13"><a href="#cb8-13" aria-hidden="true" tabindex="-1"></a>    s<span class="op">=</span><span class="st">''</span>.join(new)</span>
-<span id="cb8-14"><a href="#cb8-14" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(s)</span>
-<span id="cb8-15"><a href="#cb8-15" aria-hidden="true" tabindex="-1"></a>    i <span class="op">+=</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a>n <span class="op">=</span> <span class="dv">10</span></span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a>s <span class="op">=</span> <span class="st">'et cetera'</span></span>
+<span id="cb8-3"><a href="#cb8-3" tabindex="-1"></a><span class="bu">print</span>(s)</span>
+<span id="cb8-4"><a href="#cb8-4" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb8-5"><a href="#cb8-5" tabindex="-1"></a><span class="cf">while</span> i <span class="op">&lt;</span> n:</span>
+<span id="cb8-6"><a href="#cb8-6" tabindex="-1"></a>    <span class="co"># print('at', j)</span></span>
+<span id="cb8-7"><a href="#cb8-7" tabindex="-1"></a>    new <span class="op">=</span> <span class="st">''</span></span>
+<span id="cb8-8"><a href="#cb8-8" tabindex="-1"></a>    <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(<span class="bu">len</span>(s)):</span>
+<span id="cb8-9"><a href="#cb8-9" tabindex="-1"></a>        left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
+<span id="cb8-10"><a href="#cb8-10" tabindex="-1"></a>        right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>)<span class="op">%</span><span class="bu">len</span>(s)</span>
+<span id="cb8-11"><a href="#cb8-11" tabindex="-1"></a>        <span class="cf">if</span> s[left]<span class="op">==</span>s[right]: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
+<span id="cb8-12"><a href="#cb8-12" tabindex="-1"></a>        <span class="cf">else</span>: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
+<span id="cb8-13"><a href="#cb8-13" tabindex="-1"></a>    s<span class="op">=</span><span class="st">''</span>.join(new)</span>
+<span id="cb8-14"><a href="#cb8-14" tabindex="-1"></a>    <span class="bu">print</span>(s)</span>
+<span id="cb8-15"><a href="#cb8-15" tabindex="-1"></a>    i <span class="op">+=</span> <span class="dv">1</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -9648,37 +9650,37 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>Here’s one solution.</p>
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> string_machine(input_string, iterations):</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">"""</span></span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a><span class="co">    Takes input_string and generates a new string with -'s and *'s</span></span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="co">    corresponding to characters that have identical adjacent characters</span></span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a><span class="co">    or not, respectively.  Iterates through this procedure with the resultant</span></span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a><span class="co">    strings for the supplied number of iterations.</span></span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="co">    """</span></span>
-<span id="cb9-8"><a href="#cb9-8" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(input_string)</span>
-<span id="cb9-9"><a href="#cb9-9" aria-hidden="true" tabindex="-1"></a>    input_string_length <span class="op">=</span> <span class="bu">len</span>(input_string)</span>
-<span id="cb9-10"><a href="#cb9-10" aria-hidden="true" tabindex="-1"></a>    old <span class="op">=</span> input_string</span>
-<span id="cb9-11"><a href="#cb9-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(iterations):</span>
-<span id="cb9-12"><a href="#cb9-12" aria-hidden="true" tabindex="-1"></a>        new <span class="op">=</span> <span class="st">''</span></span>
-<span id="cb9-13"><a href="#cb9-13" aria-hidden="true" tabindex="-1"></a>        <span class="co"># iterate through characters in previous string</span></span>
-<span id="cb9-14"><a href="#cb9-14" aria-hidden="true" tabindex="-1"></a>        <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(input_string_length):</span>
-<span id="cb9-15"><a href="#cb9-15" aria-hidden="true" tabindex="-1"></a>            left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
-<span id="cb9-16"><a href="#cb9-16" aria-hidden="true" tabindex="-1"></a>            right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>) <span class="op">%</span> input_string_length  <span class="co"># ensure right index wraps around</span></span>
-<span id="cb9-17"><a href="#cb9-17" aria-hidden="true" tabindex="-1"></a>            <span class="cf">if</span> old[left] <span class="op">==</span> old[right]:</span>
-<span id="cb9-18"><a href="#cb9-18" aria-hidden="true" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
-<span id="cb9-19"><a href="#cb9-19" aria-hidden="true" tabindex="-1"></a>            <span class="cf">else</span>:</span>
-<span id="cb9-20"><a href="#cb9-20" aria-hidden="true" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
-<span id="cb9-21"><a href="#cb9-21" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(new)</span>
-<span id="cb9-22"><a href="#cb9-22" aria-hidden="true" tabindex="-1"></a>        <span class="co"># store new string as old</span></span>
-<span id="cb9-23"><a href="#cb9-23" aria-hidden="true" tabindex="-1"></a>        old <span class="op">=</span> new     </span>
-<span id="cb9-24"><a href="#cb9-24" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb9-25"><a href="#cb9-25" aria-hidden="true" tabindex="-1"></a>string_machine(<span class="st">'et cetera'</span>, <span class="dv">10</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="kw">def</span> string_machine(input_string, iterations):</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>    <span class="co">"""</span></span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a><span class="co">    Takes input_string and generates a new string with -'s and *'s</span></span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a><span class="co">    corresponding to characters that have identical adjacent characters</span></span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a><span class="co">    or not, respectively.  Iterates through this procedure with the resultant</span></span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a><span class="co">    strings for the supplied number of iterations.</span></span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a><span class="co">    """</span></span>
+<span id="cb9-8"><a href="#cb9-8" tabindex="-1"></a>    <span class="bu">print</span>(input_string)</span>
+<span id="cb9-9"><a href="#cb9-9" tabindex="-1"></a>    input_string_length <span class="op">=</span> <span class="bu">len</span>(input_string)</span>
+<span id="cb9-10"><a href="#cb9-10" tabindex="-1"></a>    old <span class="op">=</span> input_string</span>
+<span id="cb9-11"><a href="#cb9-11" tabindex="-1"></a>    <span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(iterations):</span>
+<span id="cb9-12"><a href="#cb9-12" tabindex="-1"></a>        new <span class="op">=</span> <span class="st">''</span></span>
+<span id="cb9-13"><a href="#cb9-13" tabindex="-1"></a>        <span class="co"># iterate through characters in previous string</span></span>
+<span id="cb9-14"><a href="#cb9-14" tabindex="-1"></a>        <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(input_string_length):</span>
+<span id="cb9-15"><a href="#cb9-15" tabindex="-1"></a>            left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
+<span id="cb9-16"><a href="#cb9-16" tabindex="-1"></a>            right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>) <span class="op">%</span> input_string_length  <span class="co"># ensure right index wraps around</span></span>
+<span id="cb9-17"><a href="#cb9-17" tabindex="-1"></a>            <span class="cf">if</span> old[left] <span class="op">==</span> old[right]:</span>
+<span id="cb9-18"><a href="#cb9-18" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
+<span id="cb9-19"><a href="#cb9-19" tabindex="-1"></a>            <span class="cf">else</span>:</span>
+<span id="cb9-20"><a href="#cb9-20" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
+<span id="cb9-21"><a href="#cb9-21" tabindex="-1"></a>        <span class="bu">print</span>(new)</span>
+<span id="cb9-22"><a href="#cb9-22" tabindex="-1"></a>        <span class="co"># store new string as old</span></span>
+<span id="cb9-23"><a href="#cb9-23" tabindex="-1"></a>        old <span class="op">=</span> new     </span>
+<span id="cb9-24"><a href="#cb9-24" tabindex="-1"></a></span>
+<span id="cb9-25"><a href="#cb9-25" tabindex="-1"></a>string_machine(<span class="st">'et cetera'</span>, <span class="dv">10</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -9885,8 +9887,8 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "url": "https://swcarpentry.github.io/python-novice-gapminder/aio.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/aio.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/design.html b/design.html
index cc3c8f75e..f225862aa 100644
--- a/design.html
+++ b/design.html
@@ -386,13 +386,12 @@ <h1>Lesson Design</h1>
 
         
 
-<div id="help-wanted" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="help-wanted" class="callout-inner">
-<h3 class="callout-title">Help Wanted<a class="anchor" aria-label="anchor" href="#help-wanted"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="help-wanted">Help Wanted<a class="anchor" aria-label="anchor" href="#help-wanted"></a></h3>
 <div class="callout-content">
 <p><strong>We are filling in the exercises <a href="#stage-3-learning-plan">below</a> in order to make the lesson plan
 more concrete. Contributions (both in the form of pull requests with
@@ -940,7 +939,7 @@ <h3 id="finish-1630">Finish (16:30)<a class="anchor" aria-label="anchor" href="#
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/design.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/discuss.html b/discuss.html
index 04040d4cc..6f69aef00 100644
--- a/discuss.html
+++ b/discuss.html
@@ -447,7 +447,7 @@ <h1>Discussion</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/discuss.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/exercises.html b/exercises.html
index 7db45a975..972a5ff66 100644
--- a/exercises.html
+++ b/exercises.html
@@ -447,7 +447,7 @@ <h1>Further Exercises</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/exercises.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/images.html b/images.html
index 7bba350d3..fd7419b6d 100644
--- a/images.html
+++ b/images.html
@@ -508,10 +508,11 @@ <h3 id="01-run-quit-figure-7">Figure 7</h3>
 <hr></section><section id="02-variables"><h2 class="section-heading"><a href="02-variables.html">Variables and Assignment</a></h2>
 <hr class="half-width">
 <h3 id="02-variables-figure-1">Figure 1</h3>
-<p aria-hidden="true">Image 1 of 1: ‘[decorative]’</p>
-<figure><img src="fig/2_indexing.svg" alt="" class="figure mx-auto d-block"><figcaption>A line of Python code, print(atom_name[0]),
+<p aria-hidden="true">Image 1 of 1: ‘A line of Python code, print(atom_name[0]), demonstrates that using the zero index will output just the initial letter, in this case ‘h’ for helium.’</p>
+<figure><img src="fig/2_indexing.svg" alt="A line of Python code, print(atom_name[0]), demonstrates that using the zero index will output just the initial letter, in this case ‘h’ for helium." class="figure mx-auto d-block"><div class="figcaption">A line of Python code, print(atom_name[0]),
 demonstrates that using the zero index will output just the initial
-letter, in this case ‘h’ for helium.</figcaption></figure><hr></section><section id="03-types-conversion"><h2 class="section-heading"><a href="03-types-conversion.html">Data Types and Type Conversion</a></h2>
+letter, in this case ‘h’ for helium.</div>
+</figure><hr></section><section id="03-types-conversion"><h2 class="section-heading"><a href="03-types-conversion.html">Data Types and Type Conversion</a></h2>
 <hr class="half-width"></section><section id="04-built-in"><h2 class="section-heading"><a href="04-built-in.html">Built-in Functions and Help</a></h2>
 <hr class="half-width"></section><section id="05-coffee"><h2 class="section-heading"><a href="05-coffee.html">Morning Coffee</a></h2>
 <hr class="half-width"></section><section id="06-libraries"><h2 class="section-heading"><a href="06-libraries.html">Libraries</a></h2>
@@ -613,8 +614,8 @@ <h3 id="09-plotting-figure-12">Figure 12</h3>
   "url": "https://swcarpentry.github.io/python-novice-gapminder/images.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/images.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/index.html b/index.html
index 9b28710d6..fd0ac6523 100644
--- a/index.html
+++ b/index.html
@@ -465,8 +465,8 @@ <h3 class="callout-title">Prerequisites<a class="anchor" aria-label="anchor" hre
   "url": "https://swcarpentry.github.io/python-novice-gapminder/index.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/index.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor-notes.html b/instructor-notes.html
index 4e35d67c9..c3a44900c 100644
--- a/instructor-notes.html
+++ b/instructor-notes.html
@@ -542,8 +542,8 @@ <h1>Instructor Notes</h1>
   "url": "https://swcarpentry.github.io/python-novice-gapminder/instructor-notes.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor-notes.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/01-run-quit.html b/instructor/01-run-quit.html
index 9793c7f5b..f0c8e228e 100644
--- a/instructor/01-run-quit.html
+++ b/instructor/01-run-quit.html
@@ -478,13 +478,12 @@ <h3 class="card-title">Objectives</h3>
 result</li>
 <li>Type code into the browser and see the results after your JupyterLab
 server has finished executing your code</li>
-</ul><div id="jupyterlab-what-about-jupyter-notebooks" class="callout callout">
+</ul><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="jupyterlab-what-about-jupyter-notebooks" class="callout-inner">
-<h3 class="callout-title">JupyterLab? What about Jupyter notebooks?<a class="anchor" aria-label="anchor" href="#jupyterlab-what-about-jupyter-notebooks"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="jupyterlab-what-about-jupyter-notebooks">JupyterLab? What about Jupyter notebooks?<a class="anchor" aria-label="anchor" href="#jupyterlab-what-about-jupyter-notebooks"></a></h3>
 <div class="callout-content">
 <p>JupyterLab is the <a href="https://jupyterlab.readthedocs.io/en/stable/getting_started/overview.html#overview" class="external-link">next
 stage in the evolution of the Jupyter Notebook</a>. If you have prior
@@ -518,7 +517,7 @@ <h3 id="macos---command-line">macOS - Command Line<a class="anchor" aria-label="
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">BASH<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
+<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
 </div>
 </div>
 <div class="section level3">
@@ -531,7 +530,7 @@ <h3 id="windows-users---command-line">Windows Users - Command Line<a class="anch
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">BASH<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
+<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
 </div>
 </div>
 <div class="section level3">
@@ -600,13 +599,12 @@ <h3 id="menu-bar">Menu Bar<a class="anchor" aria-label="anchor" href="#menu-bar"
 <li>
 <strong>Help:</strong> A list of JupyterLab and kernel help
 links.</li>
-</ul><div id="kernels" class="callout callout">
+</ul><div id="callout2" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="kernels" class="callout-inner">
-<h3 class="callout-title">Kernels<a class="anchor" aria-label="anchor" href="#kernels"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="kernels">Kernels<a class="anchor" aria-label="anchor" href="#kernels"></a></h3>
 <div class="callout-content">
 <p>The JupyterLab <a href="https://jupyterlab.readthedocs.io/en/stable/user/documents_kernels.html" class="external-link">docs</a>
 define kernels as “separate processes started by the server that runs
@@ -684,13 +682,12 @@ <h3 id="main-work-area">Main Work Area<a class="anchor" aria-label="anchor" href
 notebook documentation</a>.</p>
 <p align="center">
 <img alt="Example Jupyter Notebook" src="../fig/0_jupyterlab_notebook_screenshot.png" width="750" class="figure"></p>
-<div id="how-its-stored" class="callout callout">
+<div id="callout3" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="how-its-stored" class="callout-inner">
-<h3 class="callout-title">How It’s Stored<a class="anchor" aria-label="anchor" href="#how-its-stored"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="how-its-stored">How It’s Stored<a class="anchor" aria-label="anchor" href="#how-its-stored"></a></h3>
 <div class="callout-content">
 <ul><li>The notebook file is stored in a format called JSON.</li>
 <li>Just like a webpage, what’s saved looks different from what you see
@@ -737,13 +734,12 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </div>
 </div>
 </div>
-<div id="code-vs.-text" class="callout callout">
+<div id="callout4" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="code-vs.-text" class="callout-inner">
-<h3 class="callout-title">Code vs. Text<a class="anchor" aria-label="anchor" href="#code-vs.-text"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="code-vs--text">Code vs. Text<a class="anchor" aria-label="anchor" href="#code-vs--text"></a></h3>
 <div class="callout-content">
 <p>Jupyter mixes code and text in different types of blocks, called
 cells. We often use the term “code” to mean “the source code of software
@@ -984,8 +980,8 @@ <h3 class="callout-title">More Math<a class="anchor" aria-label="anchor" href="#
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="dv">7</span> <span class="op">*</span> <span class="dv">3</span></span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="dv">2</span> <span class="op">+</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="dv">7</span> <span class="op">*</span> <span class="dv">3</span></span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="dv">2</span> <span class="op">+</span> <span class="dv">1</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -1001,7 +997,7 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="dv">3</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="dv">3</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -1022,8 +1018,8 @@ <h3 class="callout-title">Change an Existing Cell from Code to
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span></span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(x)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span></span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a><span class="bu">print</span>(x)</span></code></pre>
 </div>
 <p>And then run it with <kbd>Shift</kbd>+<kbd>Return</kbd> to be sure
 that it works as a code cell. Now go back to the cell and use
@@ -1047,7 +1043,7 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span> <span class="bu">print</span>(x)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span> <span class="bu">print</span>(x)</span></code></pre>
 </div>
 </div>
 </div>
@@ -1192,7 +1188,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/01-run-quit.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-06-07",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/02-variables.html b/instructor/02-variables.html
index da9b892de..39b99623c 100644
--- a/instructor/02-variables.html
+++ b/instructor/02-variables.html
@@ -458,8 +458,8 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">42</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>first_name <span class="op">=</span> <span class="st">'Ahmed'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">42</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>first_name <span class="op">=</span> <span class="st">'Ahmed'</span></span></code></pre>
 </div>
 </li>
 </ul></section><section id="use-print-to-display-values."><h2 class="section-heading">Use <code>print</code> to display values.<a class="anchor" aria-label="anchor" href="#use-print-to-display-values."></a>
@@ -478,7 +478,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(first_name, <span class="st">'is'</span>, age, <span class="st">'years old'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(first_name, <span class="st">'is'</span>, age, <span class="st">'years old'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -497,7 +497,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(last_name)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="bu">print</span>(last_name)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -512,13 +512,12 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <ul><li>The last line of an error message is usually the most
 informative.</li>
 <li>We will look at error messages in detail <a href="17-scope.html#reading-error-messages">later</a>.</li>
-</ul><div id="variables-persist-between-cells" class="callout callout">
+</ul><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="variables-persist-between-cells" class="callout-inner">
-<h3 class="callout-title">Variables Persist Between Cells<a class="anchor" aria-label="anchor" href="#variables-persist-between-cells"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="variables-persist-between-cells">Variables Persist Between Cells<a class="anchor" aria-label="anchor" href="#variables-persist-between-cells"></a></h3>
 <div class="callout-content">
 <p>Be aware that it is the <em>order</em> of execution of cells that is
 important in a Jupyter notebook, not the order in which they appear.
@@ -531,12 +530,12 @@ <h3 class="callout-title">Variables Persist Between Cells<a class="anchor" aria-
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(myval)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a><span class="bu">print</span>(myval)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>myval <span class="op">=</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>myval <span class="op">=</span> <span class="dv">1</span></span></code></pre>
 </div>
 <p>If you execute this in order, the first cell will give an error.
 However, if you run the first cell <em>after</em> the second cell it
@@ -556,8 +555,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> age <span class="op">+</span> <span class="dv">3</span></span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Age in three years:'</span>, age)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a>age <span class="op">=</span> age <span class="op">+</span> <span class="dv">3</span></span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Age in three years:'</span>, age)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -576,13 +575,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <li>Indices are numbered from 0.</li>
 <li>Use the position’s index in square brackets to get the character at
 that position.</li>
-</ul><figure><img src="../fig/2_indexing.svg" alt="" class="figure mx-auto d-block"><figcaption>A line of Python code, print(atom_name[0]),
+</ul><figure><img src="../fig/2_indexing.svg" alt="A line of Python code, print(atom_name[0]), demonstrates that using the zero index will output just the initial letter, in this case ‘h’ for helium." class="figure mx-auto d-block"><div class="figcaption">A line of Python code, print(atom_name[0]),
 demonstrates that using the zero index will output just the initial
-letter, in this case ‘h’ for helium.</figcaption></figure><div class="codewrapper sourceCode" id="cb10">
+letter, in this case ‘h’ for helium.</div>
+</figure><div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'helium'</span></span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'helium'</span></span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -610,8 +610,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'sodium'</span></span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>:<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'sodium'</span></span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>:<span class="dv">3</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -624,7 +624,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="st">'helium'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="st">'helium'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -646,9 +646,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>flabadab <span class="op">=</span> <span class="dv">42</span></span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a>ewr_422_yY <span class="op">=</span> <span class="st">'Ahmed'</span></span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(ewr_422_yY, <span class="st">'is'</span>, flabadab, <span class="st">'years old'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>flabadab <span class="op">=</span> <span class="dv">42</span></span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a>ewr_422_yY <span class="op">=</span> <span class="st">'Ahmed'</span></span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a><span class="bu">print</span>(ewr_422_yY, <span class="st">'is'</span>, flabadab, <span class="st">'years old'</span>)</span></code></pre>
 </div>
 <ul><li>Use meaningful variable names to help other people understand what
 the program does.</li>
@@ -666,12 +666,12 @@ <h3 class="callout-title">Swapping Values<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Command  # Value of x   # Value of y   # Value of swap #</span></span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> <span class="fl">1.0</span>    <span class="co">#              #              #               #</span></span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a>y <span class="op">=</span> <span class="fl">3.0</span>    <span class="co">#              #              #               #</span></span>
-<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a>swap <span class="op">=</span> x   <span class="co">#              #              #               #</span></span>
-<span id="cb17-5"><a href="#cb17-5" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> y      <span class="co">#              #              #               #</span></span>
-<span id="cb17-6"><a href="#cb17-6" aria-hidden="true" tabindex="-1"></a>y <span class="op">=</span> swap   <span class="co">#              #              #               #</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="co"># Command  # Value of x   # Value of y   # Value of swap #</span></span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>x <span class="op">=</span> <span class="fl">1.0</span>    <span class="co">#              #              #               #</span></span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a>y <span class="op">=</span> <span class="fl">3.0</span>    <span class="co">#              #              #               #</span></span>
+<span id="cb17-4"><a href="#cb17-4" tabindex="-1"></a>swap <span class="op">=</span> x   <span class="co">#              #              #               #</span></span>
+<span id="cb17-5"><a href="#cb17-5" tabindex="-1"></a>x <span class="op">=</span> y      <span class="co">#              #              #               #</span></span>
+<span id="cb17-6"><a href="#cb17-6" tabindex="-1"></a>y <span class="op">=</span> swap   <span class="co">#              #              #               #</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -681,7 +681,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -714,9 +714,9 @@ <h3 class="callout-title">Predicting Values<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'left'</span></span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>position <span class="op">=</span> initial</span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'right'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'left'</span></span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>position <span class="op">=</span> initial</span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'right'</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -726,12 +726,12 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(position)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a><span class="bu">print</span>(position)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -766,7 +766,7 @@ <h3 class="callout-title">Challenge<a class="anchor" aria-label="anchor" href="#
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Numbers are not strings or sequences and Python will raise an error
 if you try to perform an index operation on a number. In the <a href="03-types-conversion.html">next lesson on types and type
@@ -777,8 +777,8 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">=</span> <span class="dv">123</span></span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>a <span class="op">=</span> <span class="dv">123</span></span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -788,8 +788,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">=</span> <span class="bu">str</span>(<span class="dv">123</span>)</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a>a <span class="op">=</span> <span class="bu">str</span>(<span class="dv">123</span>)</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -822,7 +822,7 @@ <h3 class="callout-title">Choosing a Name<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p><code>minutes</code> is better because <code>min</code> might mean
 something like “minimum” (and actually is an existing built-in function
@@ -843,8 +843,8 @@ <h3 class="callout-title">Slicing practice<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'carbon'</span></span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'atom_name[1:3] is:'</span>, atom_name[<span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'carbon'</span></span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'atom_name[1:3] is:'</span>, atom_name[<span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -854,7 +854,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -877,7 +877,7 @@ <h3 class="callout-title">Slicing concepts<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>species_name <span class="op">=</span> <span class="st">"Acacia buxifolia"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>species_name <span class="op">=</span> <span class="st">"Acacia buxifolia"</span></span></code></pre>
 </div>
 <p>What would these expressions return?</p>
 <ol style="list-style-type: decimal"><li><code>species_name[2:8]</code></li>
@@ -902,7 +902,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solutions</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <ol style="list-style-type: decimal"><li>
 <code>species_name[2:8]</code> returns the substring
@@ -1016,7 +1016,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/02-variables.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/03-types-conversion.html b/instructor/03-types-conversion.html
index e6bb00567..d5a51a4a9 100644
--- a/instructor/03-types-conversion.html
+++ b/instructor/03-types-conversion.html
@@ -459,7 +459,7 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="dv">52</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="dv">52</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -469,8 +469,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>fitness <span class="op">=</span> <span class="st">'average'</span></span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(fitness))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a>fitness <span class="op">=</span> <span class="st">'average'</span></span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(fitness))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -484,7 +484,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span> <span class="op">-</span> <span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span> <span class="op">-</span> <span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -494,7 +494,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'hello'</span> <span class="op">-</span> <span class="st">'h'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'hello'</span> <span class="op">-</span> <span class="st">'h'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -512,8 +512,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>full_name <span class="op">=</span> <span class="st">'Ahmed'</span> <span class="op">+</span> <span class="st">' '</span> <span class="op">+</span> <span class="st">'Walsh'</span></span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(full_name)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>full_name <span class="op">=</span> <span class="st">'Ahmed'</span> <span class="op">+</span> <span class="st">' '</span> <span class="op">+</span> <span class="st">'Walsh'</span></span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="bu">print</span>(full_name)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -528,8 +528,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>separator <span class="op">=</span> <span class="st">'='</span> <span class="op">*</span> <span class="dv">10</span></span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(separator)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>separator <span class="op">=</span> <span class="st">'='</span> <span class="op">*</span> <span class="dv">10</span></span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="bu">print</span>(separator)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -543,7 +543,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(full_name))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(full_name))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -554,7 +554,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="dv">52</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="dv">52</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -573,7 +573,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -592,8 +592,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="bu">int</span>(<span class="st">'2'</span>))</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">str</span>(<span class="dv">1</span>) <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="bu">int</span>(<span class="st">'2'</span>))</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">str</span>(<span class="dv">1</span>) <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -609,8 +609,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'half is'</span>, <span class="dv">1</span> <span class="op">/</span> <span class="fl">2.0</span>)</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'three squared is'</span>, <span class="fl">3.0</span> <span class="op">**</span> <span class="dv">2</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'half is'</span>, <span class="dv">1</span> <span class="op">/</span> <span class="fl">2.0</span>)</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'three squared is'</span>, <span class="fl">3.0</span> <span class="op">**</span> <span class="dv">2</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -626,10 +626,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">1</span></span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a>variable_two <span class="op">=</span> <span class="dv">5</span> <span class="op">*</span> variable_one</span>
-<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">2</span></span>
-<span id="cb23-4"><a href="#cb23-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first is'</span>, variable_one, <span class="st">'and second is'</span>, variable_two)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">1</span></span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a>variable_two <span class="op">=</span> <span class="dv">5</span> <span class="op">*</span> variable_one</span>
+<span id="cb23-3"><a href="#cb23-3" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">2</span></span>
+<span id="cb23-4"><a href="#cb23-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first is'</span>, variable_one, <span class="st">'and second is'</span>, variable_two)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -660,7 +660,7 @@ <h3 class="callout-title">Fractions<a class="anchor" aria-label="anchor" href="#
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>It is a floating-point number (often abbreviated “float”). It is
 possible to find out by using the built-in function
@@ -668,7 +668,7 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="fl">3.4</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="fl">3.4</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -696,15 +696,15 @@ <h3 class="callout-title">Automatic Type Conversion<a class="anchor" aria-label=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>It is a float: integers are automatically converted to floats as
 necessary.</p>
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="fl">3.25</span> <span class="op">+</span> <span class="dv">4</span></span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result, <span class="st">'is'</span>, <span class="bu">type</span>(result))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>result <span class="op">=</span> <span class="fl">3.25</span> <span class="op">+</span> <span class="dv">4</span></span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a><span class="bu">print</span>(result, <span class="st">'is'</span>, <span class="bu">type</span>(result))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -742,7 +742,7 @@ <h3 class="callout-title">Choose a Type<a class="anchor" aria-label="anchor" hre
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>The answers to the questions are:</p>
 <ol style="list-style-type: decimal"><li>Integer, since the number of days would lie between 1 and 365.</li>
@@ -775,9 +775,9 @@ <h3 class="callout-title">Division Types<a class="anchor" aria-label="anchor" hr
 <div class="codewrapper sourceCode" id="cb29">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 // 3:'</span>, <span class="dv">5</span> <span class="op">//</span> <span class="dv">3</span>)</span>
-<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 / 3:'</span>, <span class="dv">5</span> <span class="op">/</span> <span class="dv">3</span>)</span>
-<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 % 3:'</span>, <span class="dv">5</span> <span class="op">%</span> <span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 // 3:'</span>, <span class="dv">5</span> <span class="op">//</span> <span class="dv">3</span>)</span>
+<span id="cb29-2"><a href="#cb29-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 / 3:'</span>, <span class="dv">5</span> <span class="op">/</span> <span class="dv">3</span>)</span>
+<span id="cb29-3"><a href="#cb29-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 % 3:'</span>, <span class="dv">5</span> <span class="op">%</span> <span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -798,7 +798,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>We want the minimum number of surveys that reaches everyone once,
 which is the rounded up value of
@@ -810,11 +810,11 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>num_subjects <span class="op">=</span> <span class="dv">600</span></span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a>num_per_survey <span class="op">=</span> <span class="dv">42</span></span>
-<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a>num_surveys <span class="op">=</span> (num_subjects <span class="op">-</span> <span class="dv">1</span>) <span class="op">//</span> num_per_survey <span class="op">+</span> <span class="dv">1</span></span>
-<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb31-5"><a href="#cb31-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(num_subjects, <span class="st">'subjects,'</span>, num_per_survey, <span class="st">'per survey:'</span>, num_surveys)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>num_subjects <span class="op">=</span> <span class="dv">600</span></span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a>num_per_survey <span class="op">=</span> <span class="dv">42</span></span>
+<span id="cb31-3"><a href="#cb31-3" tabindex="-1"></a>num_surveys <span class="op">=</span> (num_subjects <span class="op">-</span> <span class="dv">1</span>) <span class="op">//</span> num_per_survey <span class="op">+</span> <span class="dv">1</span></span>
+<span id="cb31-4"><a href="#cb31-4" tabindex="-1"></a></span>
+<span id="cb31-5"><a href="#cb31-5" tabindex="-1"></a><span class="bu">print</span>(num_subjects, <span class="st">'subjects,'</span>, num_per_survey, <span class="st">'per survey:'</span>, num_surveys)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -839,8 +839,8 @@ <h3 class="callout-title">Strings to Numbers<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb33">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"3.4"</span>))</span>
-<span id="cb33-2"><a href="#cb33-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"float to int:"</span>, <span class="bu">int</span>(<span class="fl">3.4</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"3.4"</span>))</span>
+<span id="cb33-2"><a href="#cb33-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"float to int:"</span>, <span class="bu">int</span>(<span class="fl">3.4</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -853,7 +853,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"Hello world!"</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"Hello world!"</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -872,7 +872,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"fractional string to int:"</span>, <span class="bu">int</span>(<span class="st">"3.4"</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"fractional string to int:"</span>, <span class="bu">int</span>(<span class="st">"3.4"</span>))</span></code></pre>
 </div>
 </div>
 </div>
@@ -882,7 +882,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>What do you expect this program to do? It would not be so
 unreasonable to expect the Python 3 <code>int</code> command to convert
@@ -892,7 +892,7 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb38">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a><span class="bu">int</span>(<span class="st">"3.4"</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" tabindex="-1"></a><span class="bu">int</span>(<span class="st">"3.4"</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -909,7 +909,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb40">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a><span class="bu">int</span>(<span class="bu">float</span>(<span class="st">"3.4"</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" tabindex="-1"></a><span class="bu">int</span>(<span class="bu">float</span>(<span class="st">"3.4"</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -933,9 +933,9 @@ <h3 class="callout-title">Arithmetic with Different Types<a class="anchor" aria-
 <div class="codewrapper sourceCode" id="cb42">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" aria-hidden="true" tabindex="-1"></a>first <span class="op">=</span> <span class="fl">1.0</span></span>
-<span id="cb42-2"><a href="#cb42-2" aria-hidden="true" tabindex="-1"></a>second <span class="op">=</span> <span class="st">"1"</span></span>
-<span id="cb42-3"><a href="#cb42-3" aria-hidden="true" tabindex="-1"></a>third <span class="op">=</span> <span class="st">"1.1"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" tabindex="-1"></a>first <span class="op">=</span> <span class="fl">1.0</span></span>
+<span id="cb42-2"><a href="#cb42-2" tabindex="-1"></a>second <span class="op">=</span> <span class="st">"1"</span></span>
+<span id="cb42-3"><a href="#cb42-3" tabindex="-1"></a>third <span class="op">=</span> <span class="st">"1.1"</span></span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li><code>first + float(second)</code></li>
 <li><code>float(second) + float(third)</code></li>
@@ -951,7 +951,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Show me the solution</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <p>Answer: 1 and 4</p>
 </div>
@@ -973,9 +973,9 @@ <h3 class="callout-title">Complex Numbers<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb43">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a>a_complex_number <span class="op">=</span> <span class="dv">6</span> <span class="op">+</span> <span class="ot">2j</span></span>
-<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.real)</span>
-<span id="cb43-3"><a href="#cb43-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.imag)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" tabindex="-1"></a>a_complex_number <span class="op">=</span> <span class="dv">6</span> <span class="op">+</span> <span class="ot">2j</span></span>
+<span id="cb43-2"><a href="#cb43-2" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.real)</span>
+<span id="cb43-3"><a href="#cb43-3" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.imag)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -996,7 +996,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
 <div class="accordion-body">
 <ol style="list-style-type: decimal"><li>Standard mathematics treatments typically use <code>i</code> to
 denote an imaginary number. However, from media reports it was an early
@@ -1094,7 +1094,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/03-types-conversion.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/04-built-in.html b/instructor/04-built-in.html
index 4b5a88803..522e2fd52 100644
--- a/instructor/04-built-in.html
+++ b/instructor/04-built-in.html
@@ -447,8 +447,8 @@ <h3 class="card-title">Objectives</h3>
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="co"># This sentence isn't executed by Python.</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>adjustment <span class="op">=</span> <span class="fl">0.5</span>   <span class="co"># Neither is this - anything after '#' is ignored.</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="co"># This sentence isn't executed by Python.</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>adjustment <span class="op">=</span> <span class="fl">0.5</span>   <span class="co"># Neither is this - anything after '#' is ignored.</span></span></code></pre>
 </div>
 </section><section id="a-function-may-take-zero-or-more-arguments."><h2 class="section-heading">A function may take zero or more arguments.<a class="anchor" aria-label="anchor" href="#a-function-may-take-zero-or-more-arguments."></a>
 </h2>
@@ -470,9 +470,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'before'</span>)</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>()</span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'after'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'before'</span>)</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a><span class="bu">print</span>()</span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'after'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -490,8 +490,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">print</span>(<span class="st">'example'</span>)</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of print is'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">print</span>(<span class="st">'example'</span>)</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of print is'</span>, result)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -511,8 +511,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>))</span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">min</span>(<span class="st">'a'</span>, <span class="st">'A'</span>, <span class="st">'0'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>))</span>
+<span id="cb6-2"><a href="#cb6-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">min</span>(<span class="st">'a'</span>, <span class="st">'A'</span>, <span class="st">'0'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -533,7 +533,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="st">'a'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="st">'a'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -552,7 +552,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -563,7 +563,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>, <span class="dv">1</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>, <span class="dv">1</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -581,13 +581,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>  <span class="co"># creation of a string object </span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(my_string))       <span class="co"># the len function takes a string as an argument and returns the length of the string</span></span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.swapcase()) <span class="co"># calling the swapcase method on the my_string object</span></span>
-<span id="cb14-6"><a href="#cb14-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb14-7"><a href="#cb14-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.<span class="fu">__len__</span>())  <span class="co"># calling the internal __len__ method on the my_string object, used by len(my_string)</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>  <span class="co"># creation of a string object </span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a></span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(my_string))       <span class="co"># the len function takes a string as an argument and returns the length of the string</span></span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a></span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a><span class="bu">print</span>(my_string.swapcase()) <span class="co"># calling the swapcase method on the my_string object</span></span>
+<span id="cb14-6"><a href="#cb14-6" tabindex="-1"></a></span>
+<span id="cb14-7"><a href="#cb14-7" tabindex="-1"></a><span class="bu">print</span>(my_string.<span class="fu">__len__</span>())  <span class="co"># calling the internal __len__ method on the my_string object, used by len(my_string)</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -601,10 +601,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.isupper())          <span class="co"># Not all the letters are uppercase</span></span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.upper())            <span class="co"># This capitalizes all the letters</span></span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.upper().isupper())  <span class="co"># Now all the letters are uppercase</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a><span class="bu">print</span>(my_string.isupper())          <span class="co"># Not all the letters are uppercase</span></span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a><span class="bu">print</span>(my_string.upper())            <span class="co"># This capitalizes all the letters</span></span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a></span>
+<span id="cb16-4"><a href="#cb16-4" tabindex="-1"></a><span class="bu">print</span>(my_string.upper().isupper())  <span class="co"># Now all the letters are uppercase</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -620,7 +620,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(<span class="bu">round</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a><span class="bu">help</span>(<span class="bu">round</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -649,8 +649,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Forgot to close the quote marks around the string.</span></span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>name <span class="op">=</span> <span class="st">'Feng</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a><span class="co"># Forgot to close the quote marks around the string.</span></span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>name <span class="op">=</span> <span class="st">'Feng</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -663,8 +663,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a><span class="co"># An extra '=' in the assignment.</span></span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> <span class="op">=</span> <span class="dv">52</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a><span class="co"># An extra '=' in the assignment.</span></span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>age <span class="op">=</span> <span class="op">=</span> <span class="dv">52</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -678,7 +678,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"hello world"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"hello world"</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -704,8 +704,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">53</span></span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a>remaining <span class="op">=</span> <span class="dv">100</span> <span class="op">-</span> aege <span class="co"># mis-spelled 'age'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">53</span></span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a>remaining <span class="op">=</span> <span class="dv">100</span> <span class="op">-</span> aege <span class="co"># mis-spelled 'age'</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -734,8 +734,8 @@ <h3 class="callout-title">What Happens When<a class="anchor" aria-label="anchor"
 </ol><div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>radiance <span class="op">=</span> <span class="fl">1.0</span></span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a>radiance <span class="op">=</span> <span class="bu">max</span>(<span class="fl">2.1</span>, <span class="fl">2.0</span> <span class="op">+</span> <span class="bu">min</span>(radiance, <span class="fl">1.1</span> <span class="op">*</span> radiance <span class="op">-</span> <span class="fl">0.5</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>radiance <span class="op">=</span> <span class="fl">1.0</span></span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a>radiance <span class="op">=</span> <span class="bu">max</span>(<span class="fl">2.1</span>, <span class="fl">2.0</span> <span class="op">+</span> <span class="bu">min</span>(radiance, <span class="fl">1.1</span> <span class="op">*</span> radiance <span class="op">-</span> <span class="fl">0.5</span>))</span></code></pre>
 </div>
 </div>
 </div>
@@ -774,12 +774,12 @@ <h3 class="callout-title">Spot the Difference<a class="anchor" aria-label="ancho
 </ol><div class="codewrapper sourceCode" id="cb29">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a>easy_string <span class="op">=</span> <span class="st">"abc"</span></span>
-<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span>
-<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a>rich <span class="op">=</span> <span class="st">"gold"</span></span>
-<span id="cb29-4"><a href="#cb29-4" aria-hidden="true" tabindex="-1"></a>poor <span class="op">=</span> <span class="st">"tin"</span></span>
-<span id="cb29-5"><a href="#cb29-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span>
-<span id="cb29-6"><a href="#cb29-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" tabindex="-1"></a>easy_string <span class="op">=</span> <span class="st">"abc"</span></span>
+<span id="cb29-2"><a href="#cb29-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span>
+<span id="cb29-3"><a href="#cb29-3" tabindex="-1"></a>rich <span class="op">=</span> <span class="st">"gold"</span></span>
+<span id="cb29-4"><a href="#cb29-4" tabindex="-1"></a>poor <span class="op">=</span> <span class="st">"tin"</span></span>
+<span id="cb29-5"><a href="#cb29-5" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span>
+<span id="cb29-6"><a href="#cb29-6" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
 </div>
 </div>
 </div>
@@ -794,7 +794,7 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -804,7 +804,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -814,7 +814,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -893,13 +893,12 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </div>
 </div>
 </div>
-<div id="explore-the-python-docs" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="explore-the-python-docs" class="callout-inner">
-<h3 class="callout-title">Explore the Python docs!<a class="anchor" aria-label="anchor" href="#explore-the-python-docs"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="explore-the-python-docs">Explore the Python docs!<a class="anchor" aria-label="anchor" href="#explore-the-python-docs"></a></h3>
 <div class="callout-content">
 <p>The <a href="https://docs.python.org/3/" class="external-link">official Python
 documentation</a> is arguably the most complete source of information
@@ -999,7 +998,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/04-built-in.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/05-coffee.html b/instructor/05-coffee.html
index e12cf10ad..5f01c3508 100644
--- a/instructor/05-coffee.html
+++ b/instructor/05-coffee.html
@@ -465,7 +465,7 @@ <h1>Morning Coffee</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/05-coffee.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/06-libraries.html b/instructor/06-libraries.html
index 55d9a1ece..bf7f69a4b 100644
--- a/instructor/06-libraries.html
+++ b/instructor/06-libraries.html
@@ -450,13 +450,12 @@ <h3 class="card-title">Objectives</h3>
 <li>Many additional libraries are available from <a href="https://pypi.python.org/pypi/" class="external-link">PyPI</a> (the Python Package
 Index).</li>
 <li>We will see later how to write new libraries.</li>
-</ul><div id="libraries-and-modules" class="callout callout">
+</ul><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="libraries-and-modules" class="callout-inner">
-<h3 class="callout-title">Libraries and modules<a class="anchor" aria-label="anchor" href="#libraries-and-modules"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="libraries-and-modules">Libraries and modules<a class="anchor" aria-label="anchor" href="#libraries-and-modules"></a></h3>
 <div class="callout-content">
 <p>A library is a collection of modules, but the terms are often used
 interchangeably, especially since many libraries only consist of a
@@ -477,10 +476,10 @@ <h3 class="callout-title">Libraries and modules<a class="anchor" aria-label="anc
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pi is'</span>, math.pi)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, math.cos(math.pi))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> math</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pi is'</span>, math.pi)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, math.cos(math.pi))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -501,7 +500,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(math)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="bu">help</span>(math)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -538,9 +537,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> cos, pi</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, cos(pi))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> cos, pi</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a></span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, cos(pi))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -556,9 +555,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, m.cos(m.pi))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a></span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, m.cos(m.pi))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -621,7 +620,7 @@ <h3 class="callout-title">Locating the Right Module<a class="anchor" aria-label=
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">'ACTTGCTTGAC'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">'ACTTGCTTGAC'</span></span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>Which <a href="https://docs.python.org/3/library/" class="external-link">standard
 library</a> module could help you?</li>
@@ -648,18 +647,18 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>random_index <span class="op">=</span> randrange(<span class="bu">len</span>(bases))</span>
-<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(bases[random_index])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a></span>
+<span id="cb10-3"><a href="#cb10-3" tabindex="-1"></a>random_index <span class="op">=</span> randrange(<span class="bu">len</span>(bases))</span>
+<span id="cb10-4"><a href="#cb10-4" tabindex="-1"></a><span class="bu">print</span>(bases[random_index])</span></code></pre>
 </div>
 <p>or more compactly:</p>
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(bases[randrange(<span class="bu">len</span>(bases))])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a></span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a><span class="bu">print</span>(bases[randrange(<span class="bu">len</span>(bases))])</span></code></pre>
 </div>
 <p>Perhaps you found the <a href="https://docs.python.org/3/library/random.html#random.sample" class="external-link"><code>random.sample</code></a>
 function? It allows for slightly less typing but might be a bit harder
@@ -667,9 +666,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> sample</span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(sample(bases, <span class="dv">1</span>)[<span class="dv">0</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> sample</span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a></span>
+<span id="cb12-3"><a href="#cb12-3" tabindex="-1"></a><span class="bu">print</span>(sample(bases, <span class="dv">1</span>)[<span class="dv">0</span>])</span></code></pre>
 </div>
 <p>Note that this function returns a list of values. We will learn about
 lists in <a href="11-lists.html">episode 11</a>.</p>
@@ -678,9 +677,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> choice</span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(choice(bases))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> choice</span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a></span>
+<span id="cb13-3"><a href="#cb13-3" tabindex="-1"></a><span class="bu">print</span>(choice(bases))</span></code></pre>
 </div>
 </div>
 </div>
@@ -701,12 +700,12 @@ <h3 class="callout-title">Jigsaw Puzzle (Parson’s Problem) Programming
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>bases<span class="op">=</span><span class="st">"ACTTGCTTGAC"</span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math</span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a>___ <span class="op">=</span> random.randrange(n_bases)</span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a>___ <span class="op">=</span> <span class="bu">len</span>(bases)</span>
-<span id="cb14-6"><a href="#cb14-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base "</span>, bases[___], <span class="st">"base index"</span>, ___)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>bases<span class="op">=</span><span class="st">"ACTTGCTTGAC"</span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a><span class="im">import</span> math</span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a>___ <span class="op">=</span> random.randrange(n_bases)</span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a>___ <span class="op">=</span> <span class="bu">len</span>(bases)</span>
+<span id="cb14-6"><a href="#cb14-6" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base "</span>, bases[___], <span class="st">"base index"</span>, ___)</span></code></pre>
 </div>
 </div>
 </div>
@@ -721,12 +720,12 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math </span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">"ACTTGCTTGAC"</span> </span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a>n_bases <span class="op">=</span> <span class="bu">len</span>(bases)</span>
-<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a>idx <span class="op">=</span> random.randrange(n_bases)</span>
-<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base"</span>, bases[idx], <span class="st">"base index"</span>, idx)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="im">import</span> math </span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">"ACTTGCTTGAC"</span> </span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a>n_bases <span class="op">=</span> <span class="bu">len</span>(bases)</span>
+<span id="cb15-5"><a href="#cb15-5" tabindex="-1"></a>idx <span class="op">=</span> random.randrange(n_bases)</span>
+<span id="cb15-6"><a href="#cb15-6" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base"</span>, bases[idx], <span class="st">"base index"</span>, idx)</span></code></pre>
 </div>
 </div>
 </div>
@@ -779,9 +778,9 @@ <h3 class="callout-title">Importing With Aliases<a class="anchor" aria-label="an
 </ol><div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> ____.degrees(____.pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(____)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>angle <span class="op">=</span> ____.degrees(____.pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a><span class="bu">print</span>(____)</span></code></pre>
 </div>
 </div>
 </div>
@@ -796,17 +795,17 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
-<span id="cb18-2"><a href="#cb18-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> m.degrees(m.pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb18-3"><a href="#cb18-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
+<span id="cb18-2"><a href="#cb18-2" tabindex="-1"></a>angle <span class="op">=</span> m.degrees(m.pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb18-3"><a href="#cb18-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 <p>can be written as</p>
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> math.degrees(math.pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="im">import</span> math</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>angle <span class="op">=</span> math.degrees(math.pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 <p>Since you just wrote the code and are familiar with it, you might
 actually find the first version easier to read. But when trying to read
@@ -889,9 +888,9 @@ <h3 class="callout-title">Importing Specific Items<a class="anchor" aria-label="
 </ol><div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>____ math <span class="im">import</span> ____, ____</span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>____ math <span class="im">import</span> ____, ____</span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 </div>
 </div>
@@ -906,9 +905,9 @@ <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> degrees, pi</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> degrees, pi</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 <p>Most likely you find this version easier to read since it’s less
 dense. The main reason not to use this form of import is to avoid name
@@ -935,8 +934,8 @@ <h3 class="callout-title">Reading Error Messages<a class="anchor" aria-label="an
 </ol><div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> log</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>log(<span class="dv">0</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> log</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>log(<span class="dv">0</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -1046,7 +1045,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/06-libraries.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/07-reading-tabular.html b/instructor/07-reading-tabular.html
index da41677f7..bd01ebac2 100644
--- a/instructor/07-reading-tabular.html
+++ b/instructor/07-reading-tabular.html
@@ -451,10 +451,10 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>data_oceania <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>data_oceania <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a><span class="bu">print</span>(data_oceania)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -482,13 +482,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <li>Using descriptive dataframe names helps us distinguish between
 multiple dataframes so we won’t accidentally overwrite a dataframe or
 read from the wrong one.</li>
-</ul><div id="file-not-found" class="callout callout">
+</ul><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="file-not-found" class="callout-inner">
-<h3 class="callout-title">File Not Found<a class="anchor" aria-label="anchor" href="#file-not-found"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="file-not-found">File Not Found<a class="anchor" aria-label="anchor" href="#file-not-found"></a></h3>
 <div class="callout-content">
 <p>Our lessons store their data files in a <code>data</code>
 sub-directory, which is why the path to the file is
@@ -517,8 +516,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>data_oceania_country <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a>data_oceania_country <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -544,7 +543,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>data_oceania_country.info()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a>data_oceania_country.info()</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -590,7 +589,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.columns)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.columns)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -609,7 +608,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.T)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.T)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -637,7 +636,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.describe())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.describe())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -694,7 +693,7 @@ <h3 class="callout-title">Reading Other Data<a class="anchor" aria-label="anchor
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>To read in a CSV, we use <code>pd.read_csv</code> and pass the
 filename <code>'data/gapminder_gdp_americas.csv'</code> to it. We also
@@ -705,8 +704,8 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>data_americas <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_americas.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a>data_americas.describe()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>data_americas <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_americas.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a>data_americas.describe()</span></code></pre>
 </div>
 </div>
 </div>
@@ -736,7 +735,7 @@ <h3 class="callout-title">Inspecting Data<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <ol style="list-style-type: decimal"><li>We can check out the first five rows of <code>data_americas</code>
 by executing <code>data_americas.head()</code> which lets us view the
@@ -747,7 +746,7 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </ol><div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>data_americas.head(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a>data_americas.head(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -785,14 +784,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ol><div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>americas_flipped <span class="op">=</span> data_americas.T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>americas_flipped <span class="op">=</span> data_americas.T</span></code></pre>
 </div>
 <p>We can then view the last three columns of <code>americas</code> by
 viewing the last three rows of <code>americas_flipped</code>:</p>
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -822,14 +821,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>).T    </span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>).T    </span></code></pre>
 </div>
 <p><strong>Note:</strong> we could have done the above in a single line
 of code by ‘chaining’ the commands:</p>
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a>data_americas.T.tail(n<span class="op">=</span><span class="dv">3</span>).T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a>data_americas.T.tail(n<span class="op">=</span><span class="dv">3</span>).T</span></code></pre>
 </div>
 </div>
 </div>
@@ -867,7 +866,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>We need to specify the path to the file of interest in the call to
 <code>pd.read_csv</code>. We first need to ‘jump’ out of the folder
@@ -877,7 +876,7 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a>data_microbes <span class="op">=</span> pd.read_csv(<span class="st">'../field_data/microbes.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a>data_microbes <span class="op">=</span> pd.read_csv(<span class="st">'../field_data/microbes.csv'</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -905,22 +904,22 @@ <h3 class="callout-title">Writing Data<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>In order to write the DataFrame <code>data_americas</code> to a file
 called <code>processed.csv</code>, execute the following command:</p>
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a>data_americas.to_csv(<span class="st">'processed.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a>data_americas.to_csv(<span class="st">'processed.csv'</span>)</span></code></pre>
 </div>
 <p>For help on <code>read_csv</code> or <code>to_csv</code>, you could
 execute, for example:</p>
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(data_americas.to_csv)</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(pd.read_csv)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="bu">help</span>(data_americas.to_csv)</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a><span class="bu">help</span>(pd.read_csv)</span></code></pre>
 </div>
 <p>Note that <code>help(to_csv)</code> or <code>help(pd.to_csv)</code>
 throws an error! This is due to the fact that <code>to_csv</code> is not
@@ -1013,7 +1012,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/07-reading-tabular.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/08-data-frames.html b/instructor/08-data-frames.html
index baaa4271b..453caf7df 100644
--- a/instructor/08-data-frames.html
+++ b/instructor/08-data-frames.html
@@ -464,9 +464,9 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.iloc[<span class="dv">0</span>, <span class="dv">0</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="bu">print</span>(data.iloc[<span class="dv">0</span>, <span class="dv">0</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -480,7 +480,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -493,7 +493,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, :])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, :])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -517,7 +517,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[:, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[:, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -544,7 +544,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -570,7 +570,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">max</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">max</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -583,7 +583,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">min</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">min</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -601,12 +601,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Use a subset of data to keep output readable.</span></span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>subset <span class="op">=</span> data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>]</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Subset of data:</span><span class="ch">\n</span><span class="st">'</span>, subset)</span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Which values were greater than 10000 ?</span></span>
-<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'</span><span class="ch">\n</span><span class="st">Where are values large?</span><span class="ch">\n</span><span class="st">'</span>, subset <span class="op">&gt;</span> <span class="dv">10000</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="co"># Use a subset of data to keep output readable.</span></span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>subset <span class="op">=</span> data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>]</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Subset of data:</span><span class="ch">\n</span><span class="st">'</span>, subset)</span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a></span>
+<span id="cb15-5"><a href="#cb15-5" tabindex="-1"></a><span class="co"># Which values were greater than 10000 ?</span></span>
+<span id="cb15-6"><a href="#cb15-6" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'</span><span class="ch">\n</span><span class="st">Where are values large?</span><span class="ch">\n</span><span class="st">'</span>, subset <span class="op">&gt;</span> <span class="dv">10000</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -636,8 +636,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>mask <span class="op">=</span> subset <span class="op">&gt;</span> <span class="dv">10000</span></span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(subset[mask])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>mask <span class="op">=</span> subset <span class="op">&gt;</span> <span class="dv">10000</span></span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a><span class="bu">print</span>(subset[mask])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -657,7 +657,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(subset[subset <span class="op">&gt;</span> <span class="dv">10000</span>].describe())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="bu">print</span>(subset[subset <span class="op">&gt;</span> <span class="dv">10000</span>].describe())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -680,7 +680,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
   <h3 class="accordion-header" id="headingInstructor1">
 <div class="note-square"><i aria-hidden="true" class="callout-icon" data-feather="edit-2"></i></div>Instructor Note</h3>
 </button>
-<div id="collapseInstructor1" class="accordion-collapse collapse" data-bs-parent="#accordionInstructor1" aria-labelledby="headingInstructor1">
+<div id="collapseInstructor1" class="accordion-collapse collapse" aria-labelledby="headingInstructor1" data-bs-parent="#accordionInstructor1">
 <div class="accordion-body">
 <p>Learners often struggle here, many may not work with financial data
 and concepts so they find the example concepts difficult to get their
@@ -707,9 +707,9 @@ <h3 class="accordion-header" id="headingInstructor1">
 </ol><div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a>mask_higher <span class="op">=</span> data <span class="op">&gt;</span> data.mean()</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a>wealth_score <span class="op">=</span> mask_higher.aggregate(<span class="st">'sum'</span>, axis<span class="op">=</span><span class="dv">1</span>) <span class="op">/</span> <span class="bu">len</span>(data.columns)</span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(wealth_score)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a>mask_higher <span class="op">=</span> data <span class="op">&gt;</span> data.mean()</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a>wealth_score <span class="op">=</span> mask_higher.aggregate(<span class="st">'sum'</span>, axis<span class="op">=</span><span class="dv">1</span>) <span class="op">/</span> <span class="bu">len</span>(data.columns)</span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="bu">print</span>(wealth_score)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -753,7 +753,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.groupby(wealth_score).<span class="bu">sum</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="bu">print</span>(data.groupby(wealth_score).<span class="bu">sum</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -789,9 +789,9 @@ <h3 class="callout-title">Selection of Individual Values<a class="anchor" aria-l
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a></span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
 </div>
 <p>Write an expression to find the Per Capita GDP of Serbia in 2007.</p>
 </div>
@@ -802,14 +802,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The selection can be done by using the labels for both the row
 (“Serbia”) and the column (“gdpPercap_2007”):</p>
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Serbia'</span>, <span class="st">'gdpPercap_2007'</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Serbia'</span>, <span class="st">'gdpPercap_2007'</span>])</span></code></pre>
 </div>
 <p>The output is</p>
 <div class="codewrapper">
@@ -835,8 +835,8 @@ <h3 class="callout-title">Extent of Slicing<a class="anchor" aria-label="anchor"
 </ol><div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_europe.iloc[<span class="dv">0</span>:<span class="dv">2</span>, <span class="dv">0</span>:<span class="dv">2</span>])</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Albania'</span>:<span class="st">'Belgium'</span>, <span class="st">'gdpPercap_1952'</span>:<span class="st">'gdpPercap_1962'</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a><span class="bu">print</span>(data_europe.iloc[<span class="dv">0</span>:<span class="dv">2</span>, <span class="dv">0</span>:<span class="dv">2</span>])</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Albania'</span>:<span class="st">'Belgium'</span>, <span class="st">'gdpPercap_1952'</span>:<span class="st">'gdpPercap_1962'</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -846,7 +846,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>No, they do not produce the same output! The output of the first
 statement is:</p>
@@ -891,11 +891,11 @@ <h3 class="callout-title">Reconstructing Data<a class="anchor" aria-label="ancho
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span>
-<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span>
-<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span>
-<span id="cb31-5"><a href="#cb31-5" aria-hidden="true" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span>
+<span id="cb31-3"><a href="#cb31-3" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span>
+<span id="cb31-4"><a href="#cb31-4" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span>
+<span id="cb31-5"><a href="#cb31-5" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -905,13 +905,13 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Let’s go through this piece of code line by line.</p>
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
 </div>
 <p>This line loads the dataset containing the GDP data from all
 countries into a dataframe called <code>first</code>. The
@@ -920,7 +920,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb33">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span></code></pre>
 </div>
 <p>This line makes a selection: only those rows of <code>first</code>
 for which the ‘continent’ column matches ‘Americas’ are extracted.
@@ -932,7 +932,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span></code></pre>
 </div>
 <p>As the syntax suggests, this line drops the row from
 <code>second</code> where the label is ‘Puerto Rico’. The resulting
@@ -941,7 +941,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span></code></pre>
 </div>
 <p>Again we apply the drop function, but in this case we are dropping
 not a row but a whole column. To accomplish this, we need to specify
@@ -950,7 +950,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb36">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" aria-hidden="true" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
 </div>
 <p>The final step is to write the data that we have been working on to a
 csv file. Pandas makes this easy with the <code>to_csv()</code>
@@ -975,9 +975,9 @@ <h3 class="callout-title">Selecting Indices<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb37-2"><a href="#cb37-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.idxmin())</span>
-<span id="cb37-3"><a href="#cb37-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.idxmax())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb37-2"><a href="#cb37-2" tabindex="-1"></a><span class="bu">print</span>(data.idxmin())</span>
+<span id="cb37-3"><a href="#cb37-3" tabindex="-1"></a><span class="bu">print</span>(data.idxmax())</span></code></pre>
 </div>
 </div>
 </div>
@@ -987,7 +987,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>For each column in <code>data</code>, <code>idxmin</code> will return
 the index value corresponding to each column’s minimum;
@@ -1023,25 +1023,25 @@ <h3 class="callout-title">Practice with Selection<a class="anchor" aria-label="a
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>1:</p>
 <div class="codewrapper sourceCode" id="cb38">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a>data[<span class="st">'gdpPercap_1982'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" tabindex="-1"></a>data[<span class="st">'gdpPercap_1982'</span>]</span></code></pre>
 </div>
 <p>2:</p>
 <div class="codewrapper sourceCode" id="cb39">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">'Denmark'</span>,:]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" tabindex="-1"></a>data.loc[<span class="st">'Denmark'</span>,:]</span></code></pre>
 </div>
 <p>3:</p>
 <div class="codewrapper sourceCode" id="cb40">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a>data.loc[:,<span class="st">'gdpPercap_1985'</span>:]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" tabindex="-1"></a>data.loc[:,<span class="st">'gdpPercap_1985'</span>:]</span></code></pre>
 </div>
 <p>Pandas is smart enough to recognize the number at the end of the
 column label and does not give you an error, although no column named
@@ -1051,7 +1051,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb41">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" aria-hidden="true" tabindex="-1"></a>data[<span class="st">'gdpPercap_2007'</span>]<span class="op">/</span>data[<span class="st">'gdpPercap_1952'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" tabindex="-1"></a>data[<span class="st">'gdpPercap_2007'</span>]<span class="op">/</span>data[<span class="st">'gdpPercap_1952'</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -1086,141 +1086,141 @@ <h3 class="callout-title">Many Ways of Access<a class="anchor" aria-label="ancho
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Show me the solution</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <p>1. Access a single column:</p>
 <div class="codewrapper sourceCode" id="cb42">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb42-2"><a href="#cb42-2" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"col_name"</span>]   <span class="co"># as a Series</span></span>
-<span id="cb42-3"><a href="#cb42-3" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]] <span class="co"># as a DataFrame</span></span>
-<span id="cb42-4"><a href="#cb42-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-5"><a href="#cb42-5" aria-hidden="true" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
-<span id="cb42-6"><a href="#cb42-6" aria-hidden="true" tabindex="-1"></a>data.T.loc[<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb42-7"><a href="#cb42-7" aria-hidden="true" tabindex="-1"></a>data.T.loc[[<span class="st">"col_name"</span>]].T  <span class="co"># as a DataFrame</span></span>
-<span id="cb42-8"><a href="#cb42-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-9"><a href="#cb42-9" aria-hidden="true" tabindex="-1"></a><span class="co"># Dot notation (Series)</span></span>
-<span id="cb42-10"><a href="#cb42-10" aria-hidden="true" tabindex="-1"></a>data.col_name</span>
-<span id="cb42-11"><a href="#cb42-11" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-12"><a href="#cb42-12" aria-hidden="true" tabindex="-1"></a><span class="co"># by index (iloc)</span></span>
-<span id="cb42-13"><a href="#cb42-13" aria-hidden="true" tabindex="-1"></a>data.iloc[:, col_index]   <span class="co"># as a Series</span></span>
-<span id="cb42-14"><a href="#cb42-14" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col_index]] <span class="co"># as a DataFrame</span></span>
-<span id="cb42-15"><a href="#cb42-15" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-16"><a href="#cb42-16" aria-hidden="true" tabindex="-1"></a><span class="co"># using a mask</span></span>
-<span id="cb42-17"><a href="#cb42-17" aria-hidden="true" tabindex="-1"></a>data.T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb42-2"><a href="#cb42-2" tabindex="-1"></a>data[<span class="st">"col_name"</span>]   <span class="co"># as a Series</span></span>
+<span id="cb42-3"><a href="#cb42-3" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]] <span class="co"># as a DataFrame</span></span>
+<span id="cb42-4"><a href="#cb42-4" tabindex="-1"></a></span>
+<span id="cb42-5"><a href="#cb42-5" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
+<span id="cb42-6"><a href="#cb42-6" tabindex="-1"></a>data.T.loc[<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb42-7"><a href="#cb42-7" tabindex="-1"></a>data.T.loc[[<span class="st">"col_name"</span>]].T  <span class="co"># as a DataFrame</span></span>
+<span id="cb42-8"><a href="#cb42-8" tabindex="-1"></a></span>
+<span id="cb42-9"><a href="#cb42-9" tabindex="-1"></a><span class="co"># Dot notation (Series)</span></span>
+<span id="cb42-10"><a href="#cb42-10" tabindex="-1"></a>data.col_name</span>
+<span id="cb42-11"><a href="#cb42-11" tabindex="-1"></a></span>
+<span id="cb42-12"><a href="#cb42-12" tabindex="-1"></a><span class="co"># by index (iloc)</span></span>
+<span id="cb42-13"><a href="#cb42-13" tabindex="-1"></a>data.iloc[:, col_index]   <span class="co"># as a Series</span></span>
+<span id="cb42-14"><a href="#cb42-14" tabindex="-1"></a>data.iloc[:, [col_index]] <span class="co"># as a DataFrame</span></span>
+<span id="cb42-15"><a href="#cb42-15" tabindex="-1"></a></span>
+<span id="cb42-16"><a href="#cb42-16" tabindex="-1"></a><span class="co"># using a mask</span></span>
+<span id="cb42-17"><a href="#cb42-17" tabindex="-1"></a>data.T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
 </div>
 <p>2. Access a single row:</p>
 <div class="codewrapper sourceCode" id="cb43">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
-<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
-<span id="cb43-3"><a href="#cb43-3" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]] <span class="co"># as a DataFrame</span></span>
-<span id="cb43-4"><a href="#cb43-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb43-5"><a href="#cb43-5" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb43-6"><a href="#cb43-6" aria-hidden="true" tabindex="-1"></a>data.T[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
-<span id="cb43-7"><a href="#cb43-7" aria-hidden="true" tabindex="-1"></a>data.T[[<span class="st">"row_name"</span>]].T <span class="co"># as a DataFrame</span></span>
-<span id="cb43-8"><a href="#cb43-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb43-9"><a href="#cb43-9" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb43-10"><a href="#cb43-10" aria-hidden="true" tabindex="-1"></a>data.iloc[row_index]   <span class="co"># as a Series</span></span>
-<span id="cb43-11"><a href="#cb43-11" aria-hidden="true" tabindex="-1"></a>data.iloc[[row_index]]   <span class="co"># as a DataFrame</span></span>
-<span id="cb43-12"><a href="#cb43-12" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb43-13"><a href="#cb43-13" aria-hidden="true" tabindex="-1"></a><span class="co"># using mask</span></span>
-<span id="cb43-14"><a href="#cb43-14" aria-hidden="true" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
+<span id="cb43-2"><a href="#cb43-2" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
+<span id="cb43-3"><a href="#cb43-3" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]] <span class="co"># as a DataFrame</span></span>
+<span id="cb43-4"><a href="#cb43-4" tabindex="-1"></a></span>
+<span id="cb43-5"><a href="#cb43-5" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb43-6"><a href="#cb43-6" tabindex="-1"></a>data.T[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
+<span id="cb43-7"><a href="#cb43-7" tabindex="-1"></a>data.T[[<span class="st">"row_name"</span>]].T <span class="co"># as a DataFrame</span></span>
+<span id="cb43-8"><a href="#cb43-8" tabindex="-1"></a></span>
+<span id="cb43-9"><a href="#cb43-9" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb43-10"><a href="#cb43-10" tabindex="-1"></a>data.iloc[row_index]   <span class="co"># as a Series</span></span>
+<span id="cb43-11"><a href="#cb43-11" tabindex="-1"></a>data.iloc[[row_index]]   <span class="co"># as a DataFrame</span></span>
+<span id="cb43-12"><a href="#cb43-12" tabindex="-1"></a></span>
+<span id="cb43-13"><a href="#cb43-13" tabindex="-1"></a><span class="co"># using mask</span></span>
+<span id="cb43-14"><a href="#cb43-14" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>]</span></code></pre>
 </div>
 <p>3. Access an individual DataFrame element:</p>
 <div class="codewrapper sourceCode" id="cb44">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by column/row names</span></span>
-<span id="cb44-2"><a href="#cb44-2" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"column_name"</span>][<span class="st">"row_name"</span>]         <span class="co"># as a Series</span></span>
-<span id="cb44-3"><a href="#cb44-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-4"><a href="#cb44-4" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb44-5"><a href="#cb44-5" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
-<span id="cb44-6"><a href="#cb44-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-7"><a href="#cb44-7" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>][<span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
-<span id="cb44-8"><a href="#cb44-8" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb44-9"><a href="#cb44-9" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][[<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame</span></span>
-<span id="cb44-10"><a href="#cb44-10" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-11"><a href="#cb44-11" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, <span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
-<span id="cb44-12"><a href="#cb44-12" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], <span class="st">"col_name"</span>]  <span class="co"># as a Series. Preserves index. Column name is moved to `.name`.</span></span>
-<span id="cb44-13"><a href="#cb44-13" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, [<span class="st">"col_name"</span>]]  <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
-<span id="cb44-14"><a href="#cb44-14" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], [<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
-<span id="cb44-15"><a href="#cb44-15" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-16"><a href="#cb44-16" aria-hidden="true" tabindex="-1"></a><span class="co"># by column/row names: Dot notation</span></span>
-<span id="cb44-17"><a href="#cb44-17" aria-hidden="true" tabindex="-1"></a>data.col_name.row_name</span>
-<span id="cb44-18"><a href="#cb44-18" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-19"><a href="#cb44-19" aria-hidden="true" tabindex="-1"></a><span class="co"># by column/row indices</span></span>
-<span id="cb44-20"><a href="#cb44-20" aria-hidden="true" tabindex="-1"></a>data.iloc[row_index, col_index] <span class="co"># as a value</span></span>
-<span id="cb44-21"><a href="#cb44-21" aria-hidden="true" tabindex="-1"></a>data.iloc[[row_index], col_index] <span class="co"># as a Series. Preserves index. Column name is moved to `.name`</span></span>
-<span id="cb44-22"><a href="#cb44-22" aria-hidden="true" tabindex="-1"></a>data.iloc[row_index, [col_index]] <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
-<span id="cb44-23"><a href="#cb44-23" aria-hidden="true" tabindex="-1"></a>data.iloc[[row_index], [col_index]] <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
-<span id="cb44-24"><a href="#cb44-24" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-25"><a href="#cb44-25" aria-hidden="true" tabindex="-1"></a><span class="co"># column name + row index</span></span>
-<span id="cb44-26"><a href="#cb44-26" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"col_name"</span>][row_index]</span>
-<span id="cb44-27"><a href="#cb44-27" aria-hidden="true" tabindex="-1"></a>data.col_name[row_index]</span>
-<span id="cb44-28"><a href="#cb44-28" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"col_name"</span>].iloc[row_index]</span>
-<span id="cb44-29"><a href="#cb44-29" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-30"><a href="#cb44-30" aria-hidden="true" tabindex="-1"></a><span class="co"># column index + row name</span></span>
-<span id="cb44-31"><a href="#cb44-31" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col_index]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb44-32"><a href="#cb44-32" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col_index]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
-<span id="cb44-33"><a href="#cb44-33" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-34"><a href="#cb44-34" aria-hidden="true" tabindex="-1"></a><span class="co"># using masks</span></span>
-<span id="cb44-35"><a href="#cb44-35" aria-hidden="true" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>].T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" tabindex="-1"></a><span class="co"># by column/row names</span></span>
+<span id="cb44-2"><a href="#cb44-2" tabindex="-1"></a>data[<span class="st">"column_name"</span>][<span class="st">"row_name"</span>]         <span class="co"># as a Series</span></span>
+<span id="cb44-3"><a href="#cb44-3" tabindex="-1"></a></span>
+<span id="cb44-4"><a href="#cb44-4" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb44-5"><a href="#cb44-5" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
+<span id="cb44-6"><a href="#cb44-6" tabindex="-1"></a></span>
+<span id="cb44-7"><a href="#cb44-7" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>][<span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
+<span id="cb44-8"><a href="#cb44-8" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb44-9"><a href="#cb44-9" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][[<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame</span></span>
+<span id="cb44-10"><a href="#cb44-10" tabindex="-1"></a></span>
+<span id="cb44-11"><a href="#cb44-11" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, <span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
+<span id="cb44-12"><a href="#cb44-12" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], <span class="st">"col_name"</span>]  <span class="co"># as a Series. Preserves index. Column name is moved to `.name`.</span></span>
+<span id="cb44-13"><a href="#cb44-13" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, [<span class="st">"col_name"</span>]]  <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
+<span id="cb44-14"><a href="#cb44-14" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], [<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
+<span id="cb44-15"><a href="#cb44-15" tabindex="-1"></a></span>
+<span id="cb44-16"><a href="#cb44-16" tabindex="-1"></a><span class="co"># by column/row names: Dot notation</span></span>
+<span id="cb44-17"><a href="#cb44-17" tabindex="-1"></a>data.col_name.row_name</span>
+<span id="cb44-18"><a href="#cb44-18" tabindex="-1"></a></span>
+<span id="cb44-19"><a href="#cb44-19" tabindex="-1"></a><span class="co"># by column/row indices</span></span>
+<span id="cb44-20"><a href="#cb44-20" tabindex="-1"></a>data.iloc[row_index, col_index] <span class="co"># as a value</span></span>
+<span id="cb44-21"><a href="#cb44-21" tabindex="-1"></a>data.iloc[[row_index], col_index] <span class="co"># as a Series. Preserves index. Column name is moved to `.name`</span></span>
+<span id="cb44-22"><a href="#cb44-22" tabindex="-1"></a>data.iloc[row_index, [col_index]] <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
+<span id="cb44-23"><a href="#cb44-23" tabindex="-1"></a>data.iloc[[row_index], [col_index]] <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
+<span id="cb44-24"><a href="#cb44-24" tabindex="-1"></a></span>
+<span id="cb44-25"><a href="#cb44-25" tabindex="-1"></a><span class="co"># column name + row index</span></span>
+<span id="cb44-26"><a href="#cb44-26" tabindex="-1"></a>data[<span class="st">"col_name"</span>][row_index]</span>
+<span id="cb44-27"><a href="#cb44-27" tabindex="-1"></a>data.col_name[row_index]</span>
+<span id="cb44-28"><a href="#cb44-28" tabindex="-1"></a>data[<span class="st">"col_name"</span>].iloc[row_index]</span>
+<span id="cb44-29"><a href="#cb44-29" tabindex="-1"></a></span>
+<span id="cb44-30"><a href="#cb44-30" tabindex="-1"></a><span class="co"># column index + row name</span></span>
+<span id="cb44-31"><a href="#cb44-31" tabindex="-1"></a>data.iloc[:, [col_index]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb44-32"><a href="#cb44-32" tabindex="-1"></a>data.iloc[:, [col_index]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
+<span id="cb44-33"><a href="#cb44-33" tabindex="-1"></a></span>
+<span id="cb44-34"><a href="#cb44-34" tabindex="-1"></a><span class="co"># using masks</span></span>
+<span id="cb44-35"><a href="#cb44-35" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>].T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
 </div>
 <p>4. Access several columns:</p>
 <div class="codewrapper sourceCode" id="cb45">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb45-1"><a href="#cb45-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb45-2"><a href="#cb45-2" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
-<span id="cb45-3"><a href="#cb45-3" aria-hidden="true" tabindex="-1"></a>data.loc[:, [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
-<span id="cb45-4"><a href="#cb45-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb45-5"><a href="#cb45-5" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb45-6"><a href="#cb45-6" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb45-1"><a href="#cb45-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb45-2"><a href="#cb45-2" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
+<span id="cb45-3"><a href="#cb45-3" tabindex="-1"></a>data.loc[:, [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
+<span id="cb45-4"><a href="#cb45-4" tabindex="-1"></a></span>
+<span id="cb45-5"><a href="#cb45-5" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb45-6"><a href="#cb45-6" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]]</span></code></pre>
 </div>
 <p>5. Access several rows</p>
 <div class="codewrapper sourceCode" id="cb46">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb46-2"><a href="#cb46-2" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span>
-<span id="cb46-3"><a href="#cb46-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb46-4"><a href="#cb46-4" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb46-5"><a href="#cb46-5" aria-hidden="true" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index]]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb46-2"><a href="#cb46-2" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span>
+<span id="cb46-3"><a href="#cb46-3" tabindex="-1"></a></span>
+<span id="cb46-4"><a href="#cb46-4" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb46-5"><a href="#cb46-5" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index]]</span></code></pre>
 </div>
 <p>6. Access a subset of specific rows and columns</p>
 <div class="codewrapper sourceCode" id="cb47">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb47-1"><a href="#cb47-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by names</span></span>
-<span id="cb47-2"><a href="#cb47-2" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>], [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
-<span id="cb47-3"><a href="#cb47-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb47-4"><a href="#cb47-4" aria-hidden="true" tabindex="-1"></a><span class="co"># by indices</span></span>
-<span id="cb47-5"><a href="#cb47-5" aria-hidden="true" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index], [col1_index, col2_index, col3_index]]</span>
-<span id="cb47-6"><a href="#cb47-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb47-7"><a href="#cb47-7" aria-hidden="true" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
-<span id="cb47-8"><a href="#cb47-8" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]].iloc[[row1_index, row2_index, row3_index]]</span>
-<span id="cb47-9"><a href="#cb47-9" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb47-10"><a href="#cb47-10" aria-hidden="true" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
-<span id="cb47-11"><a href="#cb47-11" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]].loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb47-1"><a href="#cb47-1" tabindex="-1"></a><span class="co"># by names</span></span>
+<span id="cb47-2"><a href="#cb47-2" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>], [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
+<span id="cb47-3"><a href="#cb47-3" tabindex="-1"></a></span>
+<span id="cb47-4"><a href="#cb47-4" tabindex="-1"></a><span class="co"># by indices</span></span>
+<span id="cb47-5"><a href="#cb47-5" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index], [col1_index, col2_index, col3_index]]</span>
+<span id="cb47-6"><a href="#cb47-6" tabindex="-1"></a></span>
+<span id="cb47-7"><a href="#cb47-7" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
+<span id="cb47-8"><a href="#cb47-8" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]].iloc[[row1_index, row2_index, row3_index]]</span>
+<span id="cb47-9"><a href="#cb47-9" tabindex="-1"></a></span>
+<span id="cb47-10"><a href="#cb47-10" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
+<span id="cb47-11"><a href="#cb47-11" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]].loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span></code></pre>
 </div>
 <p>7. Access a subset of row and column ranges</p>
 <div class="codewrapper sourceCode" id="cb48">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb48-2"><a href="#cb48-2" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>, <span class="st">"col1"</span>:<span class="st">"col2"</span>]</span>
-<span id="cb48-3"><a href="#cb48-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb48-4"><a href="#cb48-4" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb48-5"><a href="#cb48-5" aria-hidden="true" tabindex="-1"></a>data.iloc[row1_index:row2_index, col1_index:col2_index]</span>
-<span id="cb48-6"><a href="#cb48-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb48-7"><a href="#cb48-7" aria-hidden="true" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
-<span id="cb48-8"><a href="#cb48-8" aria-hidden="true" tabindex="-1"></a>data.loc[:, <span class="st">"col1_name"</span>:<span class="st">"col2_name"</span>].iloc[row1_index:row2_index]</span>
-<span id="cb48-9"><a href="#cb48-9" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb48-10"><a href="#cb48-10" aria-hidden="true" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
-<span id="cb48-11"><a href="#cb48-11" aria-hidden="true" tabindex="-1"></a>data.iloc[:, col1_index:col2_index].loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb48-2"><a href="#cb48-2" tabindex="-1"></a>data.loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>, <span class="st">"col1"</span>:<span class="st">"col2"</span>]</span>
+<span id="cb48-3"><a href="#cb48-3" tabindex="-1"></a></span>
+<span id="cb48-4"><a href="#cb48-4" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb48-5"><a href="#cb48-5" tabindex="-1"></a>data.iloc[row1_index:row2_index, col1_index:col2_index]</span>
+<span id="cb48-6"><a href="#cb48-6" tabindex="-1"></a></span>
+<span id="cb48-7"><a href="#cb48-7" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
+<span id="cb48-8"><a href="#cb48-8" tabindex="-1"></a>data.loc[:, <span class="st">"col1_name"</span>:<span class="st">"col2_name"</span>].iloc[row1_index:row2_index]</span>
+<span id="cb48-9"><a href="#cb48-9" tabindex="-1"></a></span>
+<span id="cb48-10"><a href="#cb48-10" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
+<span id="cb48-11"><a href="#cb48-11" tabindex="-1"></a>data.iloc[:, col1_index:col2_index].loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -1241,22 +1241,22 @@ <h3 class="callout-title">Exploring available methods using the<code>dir()</code
 <div class="codewrapper sourceCode" id="cb49">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb49-1"><a href="#cb49-1" aria-hidden="true" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>   <span class="co"># creation of a string object </span></span>
-<span id="cb49-2"><a href="#cb49-2" aria-hidden="true" tabindex="-1"></a><span class="bu">dir</span>(my_string)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb49-1"><a href="#cb49-1" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>   <span class="co"># creation of a string object </span></span>
+<span id="cb49-2"><a href="#cb49-2" tabindex="-1"></a><span class="bu">dir</span>(my_string)</span></code></pre>
 </div>
 <p>This command returns:</p>
 <div class="codewrapper sourceCode" id="cb50">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb50-1"><a href="#cb50-1" aria-hidden="true" tabindex="-1"></a>[<span class="st">'__add__'</span>,</span>
-<span id="cb50-2"><a href="#cb50-2" aria-hidden="true" tabindex="-1"></a>...</span>
-<span id="cb50-3"><a href="#cb50-3" aria-hidden="true" tabindex="-1"></a><span class="st">'__subclasshook__'</span>,</span>
-<span id="cb50-4"><a href="#cb50-4" aria-hidden="true" tabindex="-1"></a><span class="st">'capitalize'</span>,</span>
-<span id="cb50-5"><a href="#cb50-5" aria-hidden="true" tabindex="-1"></a><span class="st">'casefold'</span>,</span>
-<span id="cb50-6"><a href="#cb50-6" aria-hidden="true" tabindex="-1"></a><span class="st">'center'</span>,</span>
-<span id="cb50-7"><a href="#cb50-7" aria-hidden="true" tabindex="-1"></a>...</span>
-<span id="cb50-8"><a href="#cb50-8" aria-hidden="true" tabindex="-1"></a><span class="st">'upper'</span>,</span>
-<span id="cb50-9"><a href="#cb50-9" aria-hidden="true" tabindex="-1"></a><span class="st">'zfill'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb50-1"><a href="#cb50-1" tabindex="-1"></a>[<span class="st">'__add__'</span>,</span>
+<span id="cb50-2"><a href="#cb50-2" tabindex="-1"></a>...</span>
+<span id="cb50-3"><a href="#cb50-3" tabindex="-1"></a><span class="st">'__subclasshook__'</span>,</span>
+<span id="cb50-4"><a href="#cb50-4" tabindex="-1"></a><span class="st">'capitalize'</span>,</span>
+<span id="cb50-5"><a href="#cb50-5" tabindex="-1"></a><span class="st">'casefold'</span>,</span>
+<span id="cb50-6"><a href="#cb50-6" tabindex="-1"></a><span class="st">'center'</span>,</span>
+<span id="cb50-7"><a href="#cb50-7" tabindex="-1"></a>...</span>
+<span id="cb50-8"><a href="#cb50-8" tabindex="-1"></a><span class="st">'upper'</span>,</span>
+<span id="cb50-9"><a href="#cb50-9" tabindex="-1"></a><span class="st">'zfill'</span>]</span></code></pre>
 </div>
 <p>You can use <code>help()</code> or <kbd>Shift</kbd>+<kbd>Tab</kbd> to
 get more information about what these methods do.</p>
@@ -1272,14 +1272,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
 <div class="accordion-body">
 <p>Among many choices, <code>dir()</code> lists the
 <code>median()</code> function as a possibility. Thus,</p>
 <div class="codewrapper sourceCode" id="cb51">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb51-1"><a href="#cb51-1" aria-hidden="true" tabindex="-1"></a>data.median()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb51-1"><a href="#cb51-1" tabindex="-1"></a>data.median()</span></code></pre>
 </div>
 </div>
 </div>
@@ -1378,7 +1378,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/08-data-frames.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-08-29",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/09-plotting.html b/instructor/09-plotting.html
index 31d997606..79929ef33 100644
--- a/instructor/09-plotting.html
+++ b/instructor/09-plotting.html
@@ -440,26 +440,25 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span></code></pre>
 </div>
 <ul><li>Simple plots are then (fairly) simple to create.</li>
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a>time <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>]</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>position <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">100</span>, <span class="dv">200</span>, <span class="dv">300</span>]</span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a>plt.plot(time, position)</span>
-<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a>plt.xlabel(<span class="st">'Time (hr)'</span>)</span>
-<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'Position (km)'</span>)</span></code></pre>
-</div>
-<figure><img src="../fig/9_simple_position_time_plot.svg" alt="Simple Position-Time Plot" class="figure mx-auto d-block"></figure><div id="display-all-open-figures" class="callout callout">
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a>time <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>]</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a>position <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">100</span>, <span class="dv">200</span>, <span class="dv">300</span>]</span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a></span>
+<span id="cb2-4"><a href="#cb2-4" tabindex="-1"></a>plt.plot(time, position)</span>
+<span id="cb2-5"><a href="#cb2-5" tabindex="-1"></a>plt.xlabel(<span class="st">'Time (hr)'</span>)</span>
+<span id="cb2-6"><a href="#cb2-6" tabindex="-1"></a>plt.ylabel(<span class="st">'Position (km)'</span>)</span></code></pre>
+</div>
+<figure><img src="../fig/9_simple_position_time_plot.svg" alt="Simple Position-Time Plot" class="figure mx-auto d-block"></figure><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="display-all-open-figures" class="callout-inner">
-<h3 class="callout-title">Display All Open Figures<a class="anchor" aria-label="anchor" href="#display-all-open-figures"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="display-all-open-figures">Display All Open Figures<a class="anchor" aria-label="anchor" href="#display-all-open-figures"></a></h3>
 <div class="callout-content">
 <p>In our Jupyter Notebook example, running the cell should generate the
 figure directly below the code. The figure is also included in the
@@ -471,7 +470,7 @@ <h3 class="callout-title">Display All Open Figures<a class="anchor" aria-label="
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>plt.show()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a>plt.show()</span></code></pre>
 </div>
 <p>This command can also be used within a Notebook - for instance, to
 display multiple figures if several are created by a single cell.</p>
@@ -492,23 +491,23 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-5"><a href="#cb4-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Extract year from last 4 characters of each column name</span></span>
-<span id="cb4-6"><a href="#cb4-6" aria-hidden="true" tabindex="-1"></a><span class="co"># The current column names are structured as 'gdpPercap_(year)', </span></span>
-<span id="cb4-7"><a href="#cb4-7" aria-hidden="true" tabindex="-1"></a><span class="co"># so we want to keep the (year) part only for clarity when plotting GDP vs. years</span></span>
-<span id="cb4-8"><a href="#cb4-8" aria-hidden="true" tabindex="-1"></a><span class="co"># To do this we use replace(), which removes from the string the characters stated in the argument</span></span>
-<span id="cb4-9"><a href="#cb4-9" aria-hidden="true" tabindex="-1"></a><span class="co"># This method works on strings, so we use replace() from Pandas Series.str vectorized string functions</span></span>
-<span id="cb4-10"><a href="#cb4-10" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-11"><a href="#cb4-11" aria-hidden="true" tabindex="-1"></a>years <span class="op">=</span> data.columns.<span class="bu">str</span>.replace(<span class="st">'gdpPercap_'</span>, <span class="st">''</span>)</span>
-<span id="cb4-12"><a href="#cb4-12" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-13"><a href="#cb4-13" aria-hidden="true" tabindex="-1"></a><span class="co"># Convert year values to integers, saving results back to dataframe</span></span>
-<span id="cb4-14"><a href="#cb4-14" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-15"><a href="#cb4-15" aria-hidden="true" tabindex="-1"></a>data.columns <span class="op">=</span> years.astype(<span class="bu">int</span>)</span>
-<span id="cb4-16"><a href="#cb4-16" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-17"><a href="#cb4-17" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">'Australia'</span>].plot()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a></span>
+<span id="cb4-3"><a href="#cb4-3" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb4-4"><a href="#cb4-4" tabindex="-1"></a></span>
+<span id="cb4-5"><a href="#cb4-5" tabindex="-1"></a><span class="co"># Extract year from last 4 characters of each column name</span></span>
+<span id="cb4-6"><a href="#cb4-6" tabindex="-1"></a><span class="co"># The current column names are structured as 'gdpPercap_(year)', </span></span>
+<span id="cb4-7"><a href="#cb4-7" tabindex="-1"></a><span class="co"># so we want to keep the (year) part only for clarity when plotting GDP vs. years</span></span>
+<span id="cb4-8"><a href="#cb4-8" tabindex="-1"></a><span class="co"># To do this we use replace(), which removes from the string the characters stated in the argument</span></span>
+<span id="cb4-9"><a href="#cb4-9" tabindex="-1"></a><span class="co"># This method works on strings, so we use replace() from Pandas Series.str vectorized string functions</span></span>
+<span id="cb4-10"><a href="#cb4-10" tabindex="-1"></a></span>
+<span id="cb4-11"><a href="#cb4-11" tabindex="-1"></a>years <span class="op">=</span> data.columns.<span class="bu">str</span>.replace(<span class="st">'gdpPercap_'</span>, <span class="st">''</span>)</span>
+<span id="cb4-12"><a href="#cb4-12" tabindex="-1"></a></span>
+<span id="cb4-13"><a href="#cb4-13" tabindex="-1"></a><span class="co"># Convert year values to integers, saving results back to dataframe</span></span>
+<span id="cb4-14"><a href="#cb4-14" tabindex="-1"></a></span>
+<span id="cb4-15"><a href="#cb4-15" tabindex="-1"></a>data.columns <span class="op">=</span> years.astype(<span class="bu">int</span>)</span>
+<span id="cb4-16"><a href="#cb4-16" tabindex="-1"></a></span>
+<span id="cb4-17"><a href="#cb4-17" tabindex="-1"></a>data.loc[<span class="st">'Australia'</span>].plot()</span></code></pre>
 </div>
 <figure><img src="../fig/9_gdp_australia.svg" alt="GDP plot for Australia" class="figure mx-auto d-block"></figure></section><section id="select-and-transform-data-then-plot-it."><h2 class="section-heading">Select and transform data, then plot it.<a class="anchor" aria-label="anchor" href="#select-and-transform-data-then-plot-it."></a>
 </h2>
@@ -518,8 +517,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>data.T.plot()</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>data.T.plot()</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
 </div>
 <figure><img src="../fig/9_gdp_australia_nz.svg" alt="GDP plot for Australia and New Zealand" class="figure mx-auto d-block"></figure></section><section id="many-styles-of-plot-are-available."><h2 class="section-heading">Many styles of plot are available.<a class="anchor" aria-label="anchor" href="#many-styles-of-plot-are-available."></a>
 </h2>
@@ -527,9 +526,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>plt.style.use(<span class="st">'ggplot'</span>)</span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a>data.T.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
-<span id="cb6-3"><a href="#cb6-3" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a>plt.style.use(<span class="st">'ggplot'</span>)</span>
+<span id="cb6-2"><a href="#cb6-2" tabindex="-1"></a>data.T.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
+<span id="cb6-3"><a href="#cb6-3" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
 </div>
 <figure><img src="../fig/9_gdp_bar.svg" alt="GDP barplot for Australia" class="figure mx-auto d-block"></figure></section><section id="data-can-also-be-plotted-by-calling-the-matplotlib-plot-function-directly."><h2 class="section-heading">Data can also be plotted by calling the <code>matplotlib</code>
 <code>plot</code> function directly.<a class="anchor" aria-label="anchor" href="#data-can-also-be-plotted-by-calling-the-matplotlib-plot-function-directly."></a>
@@ -544,36 +543,35 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>years <span class="op">=</span> data.columns</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'g--'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>years <span class="op">=</span> data.columns</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a></span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'g--'</span>)</span></code></pre>
 </div>
 <figure><img src="../fig/9_gdp_australia_formatted.svg" alt="GDP formatted plot for Australia" class="figure mx-auto d-block"></figure></section><section id="can-plot-many-sets-of-data-together."><h2 class="section-heading">Can plot many sets of data together.<a class="anchor" aria-label="anchor" href="#can-plot-many-sets-of-data-together."></a>
 </h2>
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Select two countries' worth of data.</span></span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
-<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a>gdp_nz <span class="op">=</span> data.loc[<span class="st">'New Zealand'</span>]</span>
-<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb8-5"><a href="#cb8-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Plot with differently-colored markers.</span></span>
-<span id="cb8-6"><a href="#cb8-6" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'b-'</span>, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
-<span id="cb8-7"><a href="#cb8-7" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_nz, <span class="st">'g-'</span>, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span>
-<span id="cb8-8"><a href="#cb8-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb8-9"><a href="#cb8-9" aria-hidden="true" tabindex="-1"></a><span class="co"># Create legend.</span></span>
-<span id="cb8-10"><a href="#cb8-10" aria-hidden="true" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'upper left'</span>)</span>
-<span id="cb8-11"><a href="#cb8-11" aria-hidden="true" tabindex="-1"></a>plt.xlabel(<span class="st">'Year'</span>)</span>
-<span id="cb8-12"><a href="#cb8-12" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita ($)'</span>)</span></code></pre>
-</div>
-<div id="adding-a-legend" class="callout callout">
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="co"># Select two countries' worth of data.</span></span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
+<span id="cb8-3"><a href="#cb8-3" tabindex="-1"></a>gdp_nz <span class="op">=</span> data.loc[<span class="st">'New Zealand'</span>]</span>
+<span id="cb8-4"><a href="#cb8-4" tabindex="-1"></a></span>
+<span id="cb8-5"><a href="#cb8-5" tabindex="-1"></a><span class="co"># Plot with differently-colored markers.</span></span>
+<span id="cb8-6"><a href="#cb8-6" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'b-'</span>, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
+<span id="cb8-7"><a href="#cb8-7" tabindex="-1"></a>plt.plot(years, gdp_nz, <span class="st">'g-'</span>, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span>
+<span id="cb8-8"><a href="#cb8-8" tabindex="-1"></a></span>
+<span id="cb8-9"><a href="#cb8-9" tabindex="-1"></a><span class="co"># Create legend.</span></span>
+<span id="cb8-10"><a href="#cb8-10" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'upper left'</span>)</span>
+<span id="cb8-11"><a href="#cb8-11" tabindex="-1"></a>plt.xlabel(<span class="st">'Year'</span>)</span>
+<span id="cb8-12"><a href="#cb8-12" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita ($)'</span>)</span></code></pre>
+</div>
+<div id="callout2" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="adding-a-legend" class="callout-inner">
-<h3 class="callout-title">Adding a Legend<a class="anchor" aria-label="anchor" href="#adding-a-legend"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="adding-a-legend">Adding a Legend<a class="anchor" aria-label="anchor" href="#adding-a-legend"></a></h3>
 <div class="callout-content">
 <p>Often when plotting multiple datasets on the same figure it is
 desirable to have a legend describing the data.</p>
@@ -582,14 +580,14 @@ <h3 class="callout-title">Adding a Legend<a class="anchor" aria-label="anchor" h
 </ul><div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_australia, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_nz, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>plt.plot(years, gdp_australia, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>plt.plot(years, gdp_nz, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span></code></pre>
 </div>
 <ul><li>Instruct <code>matplotlib</code> to create the legend.</li>
 </ul><div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a>plt.legend()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a>plt.legend()</span></code></pre>
 </div>
 <p>By default matplotlib will attempt to place the legend in a suitable
 position. If you would rather specify a position this can be done with
@@ -606,12 +604,12 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>plt.scatter(gdp_australia, gdp_nz)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>plt.scatter(gdp_australia, gdp_nz)</span></code></pre>
 </div>
 <figure><img src="../fig/9_gdp_correlation_plt.svg" alt="GDP correlation using plt.scatter" class="figure mx-auto d-block"></figure><div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a>data.T.plot.scatter(x <span class="op">=</span> <span class="st">'Australia'</span>, y <span class="op">=</span> <span class="st">'New Zealand'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a>data.T.plot.scatter(x <span class="op">=</span> <span class="st">'Australia'</span>, y <span class="op">=</span> <span class="st">'New Zealand'</span>)</span></code></pre>
 </div>
 <figure><img src="../fig/9_gdp_correlation_data.svg" alt="GDP correlation using data.T.plot.scatter" class="figure mx-auto d-block"></figure><div id="minima-and-maxima" class="callout challenge">
 <div class="callout-square">
@@ -627,11 +625,11 @@ <h3 class="callout-title">Minima and Maxima<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a>data_europe.____.plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
-<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a>data_europe.____</span>
-<span id="cb13-4"><a href="#cb13-4" aria-hidden="true" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
-<span id="cb13-5"><a href="#cb13-5" aria-hidden="true" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a>data_europe.____.plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
+<span id="cb13-3"><a href="#cb13-3" tabindex="-1"></a>data_europe.____</span>
+<span id="cb13-4"><a href="#cb13-4" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
+<span id="cb13-5"><a href="#cb13-5" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -641,16 +639,16 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a>data_europe.<span class="bu">min</span>().plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a>data_europe.<span class="bu">max</span>().plot(label<span class="op">=</span><span class="st">'max'</span>)</span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a>data_europe.<span class="bu">min</span>().plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a>data_europe.<span class="bu">max</span>().plot(label<span class="op">=</span><span class="st">'max'</span>)</span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
 </div>
 <figure><img src="../fig/9_minima_maxima_solution.png" alt="Minima Maxima Solution" class="figure mx-auto d-block"></figure></div>
 </div>
@@ -676,13 +674,13 @@ <h3 class="callout-title">Correlations<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>data_asia.describe().T.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'min'</span>, y<span class="op">=</span><span class="st">'max'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>data_asia.describe().T.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'min'</span>, y<span class="op">=</span><span class="st">'max'</span>)</span></code></pre>
 </div>
 <figure><img src="../fig/9_correlations_solution1.svg" alt="Correlations Solution 1" class="figure mx-auto d-block"></figure><p>No particular correlations can be seen between the minimum and
 maximum gdp values year on year. It seems the fortunes of asian
@@ -705,10 +703,10 @@ <h3 class="callout-title">Correlations<em>(continued)</em><a class="anchor" aria
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a>data_asia.<span class="bu">max</span>().plot()</span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmax())</span>
-<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmin())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a>data_asia.<span class="bu">max</span>().plot()</span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmax())</span>
+<span id="cb16-4"><a href="#cb16-4" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmin())</span></code></pre>
 </div>
 </div>
 </div>
@@ -718,7 +716,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <figure><img src="../fig/9_correlations_solution2.png" alt="Correlations Solution 2" class="figure mx-auto d-block"></figure><p>Seems the variability in this value is due to a sharp drop after
 1972. Some geopolitics at play perhaps? Given the dominance of oil
@@ -742,9 +740,9 @@ <h3 class="callout-title">More Correlations<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>data_all <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>data_all.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'gdpPercap_2007'</span>, y<span class="op">=</span><span class="st">'lifeExp_2007'</span>,</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a>              s<span class="op">=</span>data_all[<span class="st">'pop_2007'</span>]<span class="op">/</span><span class="fl">1e6</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>data_all <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>data_all.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'gdpPercap_2007'</span>, y<span class="op">=</span><span class="st">'lifeExp_2007'</span>,</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a>              s<span class="op">=</span>data_all[<span class="st">'pop_2007'</span>]<span class="op">/</span><span class="fl">1e6</span>)</span></code></pre>
 </div>
 <p>Using online help and other resources, explain what each argument to
 <code>plot</code> does.</p>
@@ -756,7 +754,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <figure><img src="../fig/9_more_correlations_solution.svg" alt="More Correlations Solution" class="figure mx-auto d-block"></figure><p>A good place to look is the documentation for the plot function -
 help(data_all.plot).</p>
@@ -771,13 +769,12 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </div>
 </div>
 </div>
-<div id="saving-your-plot-to-a-file" class="callout callout">
+<div id="callout3" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="saving-your-plot-to-a-file" class="callout-inner">
-<h3 class="callout-title">Saving your plot to a file<a class="anchor" aria-label="anchor" href="#saving-your-plot-to-a-file"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="saving-your-plot-to-a-file">Saving your plot to a file<a class="anchor" aria-label="anchor" href="#saving-your-plot-to-a-file"></a></h3>
 <div class="callout-content">
 <p>If you are satisfied with the plot you see you may want to save it to
 a file, perhaps to include it in a publication. There is a function in
@@ -786,7 +783,7 @@ <h3 class="callout-title">Saving your plot to a file<a class="anchor" aria-label
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>plt.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>plt.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
 </div>
 <p>will save the current figure to the file <code>my_figure.png</code>.
 The file format will automatically be deduced from the file name
@@ -805,20 +802,19 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a>data.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>fig <span class="op">=</span> plt.gcf() <span class="co"># get current figure</span></span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a>fig.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a>data.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>fig <span class="op">=</span> plt.gcf() <span class="co"># get current figure</span></span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a>fig.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
 </div>
 </div>
 </div>
 </div>
-<div id="making-your-plots-accessible" class="callout callout">
+<div id="callout4" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="making-your-plots-accessible" class="callout-inner">
-<h3 class="callout-title">Making your plots accessible<a class="anchor" aria-label="anchor" href="#making-your-plots-accessible"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="making-your-plots-accessible">Making your plots accessible<a class="anchor" aria-label="anchor" href="#making-your-plots-accessible"></a></h3>
 <div class="callout-content">
 <p>Whenever you are generating plots to go into a paper or a
 presentation, there are a few things you can do to make sure that
@@ -920,7 +916,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/09-plotting.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-06-08",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/10-lunch.html b/instructor/10-lunch.html
index 9753a1cdf..d16e2779e 100644
--- a/instructor/10-lunch.html
+++ b/instructor/10-lunch.html
@@ -458,7 +458,7 @@ <h1>Lunch</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/10-lunch.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/11-lists.html b/instructor/11-lists.html
index e06d6fad2..ea0ab7769 100644
--- a/instructor/11-lists.html
+++ b/instructor/11-lists.html
@@ -444,9 +444,9 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>pressures <span class="op">=</span> [<span class="fl">0.273</span>, <span class="fl">0.275</span>, <span class="fl">0.277</span>, <span class="fl">0.275</span>, <span class="fl">0.276</span>]</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures:'</span>, pressures)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'length:'</span>, <span class="bu">len</span>(pressures))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>pressures <span class="op">=</span> [<span class="fl">0.273</span>, <span class="fl">0.275</span>, <span class="fl">0.277</span>, <span class="fl">0.275</span>, <span class="fl">0.276</span>]</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures:'</span>, pressures)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'length:'</span>, <span class="bu">len</span>(pressures))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -460,8 +460,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth item of pressures:'</span>, pressures[<span class="dv">0</span>])</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'fourth item of pressures:'</span>, pressures[<span class="dv">4</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth item of pressures:'</span>, pressures[<span class="dv">0</span>])</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'fourth item of pressures:'</span>, pressures[<span class="dv">4</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -476,8 +476,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>pressures[<span class="dv">0</span>] <span class="op">=</span> <span class="fl">0.265</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures is now:'</span>, pressures)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>pressures[<span class="dv">0</span>] <span class="op">=</span> <span class="fl">0.265</span></span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures is now:'</span>, pressures)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -491,10 +491,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is initially:'</span>, primes)</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>primes.append(<span class="dv">7</span>)</span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has become:'</span>, primes)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is initially:'</span>, primes)</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a>primes.append(<span class="dv">7</span>)</span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has become:'</span>, primes)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -518,13 +518,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>teen_primes <span class="op">=</span> [<span class="dv">11</span>, <span class="dv">13</span>, <span class="dv">17</span>, <span class="dv">19</span>]</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>middle_aged_primes <span class="op">=</span> [<span class="dv">37</span>, <span class="dv">41</span>, <span class="dv">43</span>, <span class="dv">47</span>]</span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is currently:'</span>, primes)</span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a>primes.extend(teen_primes)</span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has now become:'</span>, primes)</span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a>primes.append(middle_aged_primes)</span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has finally become:'</span>, primes)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>teen_primes <span class="op">=</span> [<span class="dv">11</span>, <span class="dv">13</span>, <span class="dv">17</span>, <span class="dv">19</span>]</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>middle_aged_primes <span class="op">=</span> [<span class="dv">37</span>, <span class="dv">41</span>, <span class="dv">43</span>, <span class="dv">47</span>]</span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is currently:'</span>, primes)</span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a>primes.extend(teen_primes)</span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has now become:'</span>, primes)</span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a>primes.append(middle_aged_primes)</span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has finally become:'</span>, primes)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -547,10 +547,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>, <span class="dv">7</span>, <span class="dv">9</span>]</span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes before removing last item:'</span>, primes)</span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a><span class="kw">del</span> primes[<span class="dv">4</span>]</span>
-<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes after removing last item:'</span>, primes)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>, <span class="dv">7</span>, <span class="dv">9</span>]</span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes before removing last item:'</span>, primes)</span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a><span class="kw">del</span> primes[<span class="dv">4</span>]</span>
+<span id="cb11-4"><a href="#cb11-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes after removing last item:'</span>, primes)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -572,7 +572,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>goals <span class="op">=</span> [<span class="dv">1</span>, <span class="st">'Create lists.'</span>, <span class="dv">2</span>, <span class="st">'Extract items from lists.'</span>, <span class="dv">3</span>, <span class="st">'Modify lists.'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>goals <span class="op">=</span> [<span class="dv">1</span>, <span class="st">'Create lists.'</span>, <span class="dv">2</span>, <span class="st">'Extract items from lists.'</span>, <span class="dv">3</span>, <span class="st">'Modify lists.'</span>]</span></code></pre>
 </div>
 </section><section id="character-strings-can-be-indexed-like-lists."><h2 class="section-heading">Character strings can be indexed like lists.<a class="anchor" aria-label="anchor" href="#character-strings-can-be-indexed-like-lists."></a>
 </h2>
@@ -581,9 +581,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'carbon'</span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth character:'</span>, element[<span class="dv">0</span>])</span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'third character:'</span>, element[<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'carbon'</span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth character:'</span>, element[<span class="dv">0</span>])</span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'third character:'</span>, element[<span class="dv">3</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -604,7 +604,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>element[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'C'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>element[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'C'</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -623,7 +623,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'99th element of element is:'</span>, element[<span class="dv">99</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'99th element of element is:'</span>, element[<span class="dv">99</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -643,13 +643,13 @@ <h3 class="callout-title">Fill in the Blanks<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> ____</span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>values.____(<span class="dv">1</span>)</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a>values.____(<span class="dv">3</span>)</span>
-<span id="cb20-4"><a href="#cb20-4" aria-hidden="true" tabindex="-1"></a>values.____(<span class="dv">5</span>)</span>
-<span id="cb20-5"><a href="#cb20-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
-<span id="cb20-6"><a href="#cb20-6" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> values[____]</span>
-<span id="cb20-7"><a href="#cb20-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>values <span class="op">=</span> ____</span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>values.____(<span class="dv">1</span>)</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a>values.____(<span class="dv">3</span>)</span>
+<span id="cb20-4"><a href="#cb20-4" tabindex="-1"></a>values.____(<span class="dv">5</span>)</span>
+<span id="cb20-5"><a href="#cb20-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
+<span id="cb20-6"><a href="#cb20-6" tabindex="-1"></a>values <span class="op">=</span> values[____]</span>
+<span id="cb20-7"><a href="#cb20-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -670,13 +670,13 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> []</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>values.append(<span class="dv">1</span>)</span>
-<span id="cb22-3"><a href="#cb22-3" aria-hidden="true" tabindex="-1"></a>values.append(<span class="dv">3</span>)</span>
-<span id="cb22-4"><a href="#cb22-4" aria-hidden="true" tabindex="-1"></a>values.append(<span class="dv">5</span>)</span>
-<span id="cb22-5"><a href="#cb22-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
-<span id="cb22-6"><a href="#cb22-6" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> values[<span class="dv">1</span>:]</span>
-<span id="cb22-7"><a href="#cb22-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>values <span class="op">=</span> []</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>values.append(<span class="dv">1</span>)</span>
+<span id="cb22-3"><a href="#cb22-3" tabindex="-1"></a>values.append(<span class="dv">3</span>)</span>
+<span id="cb22-4"><a href="#cb22-4" tabindex="-1"></a>values.append(<span class="dv">5</span>)</span>
+<span id="cb22-5"><a href="#cb22-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
+<span id="cb22-6"><a href="#cb22-6" tabindex="-1"></a>values <span class="op">=</span> values[<span class="dv">1</span>:]</span>
+<span id="cb22-7"><a href="#cb22-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
 </div>
 </div>
 </div>
@@ -725,8 +725,8 @@ <h3 class="callout-title">From Strings to Lists and Back<a class="anchor" aria-l
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'string to list:'</span>, <span class="bu">list</span>(<span class="st">'tin'</span>))</span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'list to string:'</span>, <span class="st">''</span>.join([<span class="st">'g'</span>, <span class="st">'o'</span>, <span class="st">'l'</span>, <span class="st">'d'</span>]))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'string to list:'</span>, <span class="bu">list</span>(<span class="st">'tin'</span>))</span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'list to string:'</span>, <span class="st">''</span>.join([<span class="st">'g'</span>, <span class="st">'o'</span>, <span class="st">'l'</span>, <span class="st">'d'</span>]))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -771,8 +771,8 @@ <h3 class="callout-title">Working With the End<a class="anchor" aria-label="anch
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'helium'</span></span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'helium'</span></span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>How does Python interpret a negative index?</li>
 <li>If a list or string has N elements, what is the most negative index
@@ -819,9 +819,9 @@ <h3 class="callout-title">Stepping Through a List<a class="anchor" aria-label="a
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'fluorine'</span></span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="dv">2</span>])</span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'fluorine'</span></span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="dv">2</span>])</span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>If we write a slice as <code>low:high:stride</code>, what does
 <code>stride</code> do?</li>
@@ -841,8 +841,8 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>furn</span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>eniroulf</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>furn</span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>eniroulf</span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>
 <code>stride</code> is the step size of the slice.</li>
@@ -867,9 +867,9 @@ <h3 class="callout-title">Slice Bounds<a class="anchor" aria-label="anchor" href
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'lithium'</span></span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[<span class="dv">0</span>:<span class="dv">20</span>])</span>
-<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'lithium'</span></span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a><span class="bu">print</span>(element[<span class="dv">0</span>:<span class="dv">20</span>])</span>
+<span id="cb28-3"><a href="#cb28-3" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -907,18 +907,18 @@ <h3 class="callout-title">Sort and Sorted<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program A</span></span>
-<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb30-3"><a href="#cb30-3" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">sorted</span>(letters)</span>
-<span id="cb30-4"><a href="#cb30-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a><span class="co"># Program A</span></span>
+<span id="cb30-2"><a href="#cb30-2" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb30-3"><a href="#cb30-3" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">sorted</span>(letters)</span>
+<span id="cb30-4"><a href="#cb30-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program B</span></span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> letters.sort()</span>
-<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a><span class="co"># Program B</span></span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb31-3"><a href="#cb31-3" tabindex="-1"></a>result <span class="op">=</span> letters.sort()</span>
+<span id="cb31-4"><a href="#cb31-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -964,20 +964,20 @@ <h3 class="callout-title">Copying (or Not)<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program A</span></span>
-<span id="cb34-2"><a href="#cb34-2" aria-hidden="true" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb34-3"><a href="#cb34-3" aria-hidden="true" tabindex="-1"></a>new <span class="op">=</span> old      <span class="co"># simple assignment</span></span>
-<span id="cb34-4"><a href="#cb34-4" aria-hidden="true" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
-<span id="cb34-5"><a href="#cb34-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a><span class="co"># Program A</span></span>
+<span id="cb34-2"><a href="#cb34-2" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb34-3"><a href="#cb34-3" tabindex="-1"></a>new <span class="op">=</span> old      <span class="co"># simple assignment</span></span>
+<span id="cb34-4"><a href="#cb34-4" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
+<span id="cb34-5"><a href="#cb34-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program B</span></span>
-<span id="cb35-2"><a href="#cb35-2" aria-hidden="true" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb35-3"><a href="#cb35-3" aria-hidden="true" tabindex="-1"></a>new <span class="op">=</span> old[:]   <span class="co"># assigning a slice</span></span>
-<span id="cb35-4"><a href="#cb35-4" aria-hidden="true" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
-<span id="cb35-5"><a href="#cb35-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a><span class="co"># Program B</span></span>
+<span id="cb35-2"><a href="#cb35-2" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb35-3"><a href="#cb35-3" tabindex="-1"></a>new <span class="op">=</span> old[:]   <span class="co"># assigning a slice</span></span>
+<span id="cb35-4"><a href="#cb35-4" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
+<span id="cb35-5"><a href="#cb35-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
 </div>
 </div>
 </div>
@@ -1091,7 +1091,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/11-lists.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-07-24",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/12-for-loops.html b/instructor/12-for-loops.html
index 9b3636c3f..1fe614903 100644
--- a/instructor/12-for-loops.html
+++ b/instructor/12-for-loops.html
@@ -445,16 +445,16 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 <ul><li>This <code>for</code> loop is equivalent to:</li>
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">2</span>)</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">3</span>)</span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">2</span>)</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">3</span>)</span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span>)</span></code></pre>
 </div>
 <ul><li>And the <code>for</code> loop’s output is:</li>
 </ul><div class="codewrapper">
@@ -470,8 +470,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <hr class="half-width"><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 <ul><li>The collection, <code>[2, 3, 5]</code>, is what the loop is being
 run on.</li>
@@ -494,8 +494,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="bu">print</span>(number)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -506,8 +506,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>firstName <span class="op">=</span> <span class="st">"Jon"</span></span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>  lastName <span class="op">=</span> <span class="st">"Smith"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>firstName <span class="op">=</span> <span class="st">"Jon"</span></span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>  lastName <span class="op">=</span> <span class="st">"Smith"</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -528,8 +528,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 </ul><div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> kitten <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(kitten)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="cf">for</span> kitten <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>    <span class="bu">print</span>(kitten)</span></code></pre>
 </div>
 </section><section id="the-body-of-a-loop-can-contain-many-statements."><h2 class="section-heading">The body of a loop can contain many statements.<a class="anchor" aria-label="anchor" href="#the-body-of-a-loop-can-contain-many-statements."></a>
 </h2>
@@ -538,11 +538,11 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> p <span class="kw">in</span> primes:</span>
-<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>    squared <span class="op">=</span> p <span class="op">**</span> <span class="dv">2</span></span>
-<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a>    cubed <span class="op">=</span> p <span class="op">**</span> <span class="dv">3</span></span>
-<span id="cb10-5"><a href="#cb10-5" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(p, squared, cubed)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a><span class="cf">for</span> p <span class="kw">in</span> primes:</span>
+<span id="cb10-3"><a href="#cb10-3" tabindex="-1"></a>    squared <span class="op">=</span> p <span class="op">**</span> <span class="dv">2</span></span>
+<span id="cb10-4"><a href="#cb10-4" tabindex="-1"></a>    cubed <span class="op">=</span> p <span class="op">**</span> <span class="dv">3</span></span>
+<span id="cb10-5"><a href="#cb10-5" tabindex="-1"></a>    <span class="bu">print</span>(p, squared, cubed)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -567,9 +567,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'a range is not a list: range(0, 3)'</span>)</span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>, <span class="dv">3</span>):</span>
-<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'a range is not a list: range(0, 3)'</span>)</span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>, <span class="dv">3</span>):</span>
+<span id="cb12-3"><a href="#cb12-3" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -589,11 +589,11 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Sum the first 10 integers.</span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a>   total <span class="op">=</span> total <span class="op">+</span> (number <span class="op">+</span> <span class="dv">1</span>)</span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a><span class="co"># Sum the first 10 integers.</span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a>   total <span class="op">=</span> total <span class="op">+</span> (number <span class="op">+</span> <span class="dv">1</span>)</span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -626,7 +626,7 @@ <h3 class="callout-title">Classifying Errors<a class="anchor" aria-label="anchor
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>An IndentationError is a syntax error. Programs with syntax errors
 cannot be started. A program with a runtime error will start but an
@@ -649,9 +649,9 @@ <h3 class="callout-title">Tracing Execution<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> <span class="st">"tin"</span>:</span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> <span class="st">"tin"</span>:</span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="dv">1</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -661,7 +661,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <table class="table"><thead><tr class="header"><th>Line no</th>
 <th>Variables</th>
@@ -696,11 +696,11 @@ <h3 class="callout-title">Reversing a String<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> ____</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
-<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> ____</span>
-<span id="cb17-5"><a href="#cb17-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>result <span class="op">=</span> ____</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
+<span id="cb17-4"><a href="#cb17-4" tabindex="-1"></a>    result <span class="op">=</span> ____</span>
+<span id="cb17-5"><a href="#cb17-5" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -710,16 +710,16 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
-<span id="cb18-2"><a href="#cb18-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb18-3"><a href="#cb18-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
-<span id="cb18-4"><a href="#cb18-4" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> char <span class="op">+</span> result</span>
-<span id="cb18-5"><a href="#cb18-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
+<span id="cb18-2"><a href="#cb18-2" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb18-3"><a href="#cb18-3" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
+<span id="cb18-4"><a href="#cb18-4" tabindex="-1"></a>    result <span class="op">=</span> char <span class="op">+</span> result</span>
+<span id="cb18-5"><a href="#cb18-5" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -738,11 +738,11 @@ <h3 class="callout-title">Practice Accumulating<a class="anchor" aria-label="anc
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Total length of the strings in the list: ["red", "green", "blue"] =&gt; 12</span></span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb19-4"><a href="#cb19-4" aria-hidden="true" tabindex="-1"></a>    ____ <span class="op">=</span> ____ <span class="op">+</span> <span class="bu">len</span>(word)</span>
-<span id="cb19-5"><a href="#cb19-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="co"># Total length of the strings in the list: ["red", "green", "blue"] =&gt; 12</span></span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb19-4"><a href="#cb19-4" tabindex="-1"></a>    ____ <span class="op">=</span> ____ <span class="op">+</span> <span class="bu">len</span>(word)</span>
+<span id="cb19-5"><a href="#cb19-5" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
 </div>
 </div>
 </div>
@@ -752,15 +752,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="bu">len</span>(word)</span>
-<span id="cb20-4"><a href="#cb20-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="bu">len</span>(word)</span>
+<span id="cb20-4"><a href="#cb20-4" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
 </div>
 </div>
 </div>
@@ -777,11 +777,11 @@ <h3 class="callout-title">Practice Accumulating<em>(continued)</em><a class="anc
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="co"># List of word lengths: ["red", "green", "blue"] =&gt; [3, 5, 4]</span></span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a>lengths <span class="op">=</span> ____</span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb21-4"><a href="#cb21-4" aria-hidden="true" tabindex="-1"></a>    lengths.____(____)</span>
-<span id="cb21-5"><a href="#cb21-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a><span class="co"># List of word lengths: ["red", "green", "blue"] =&gt; [3, 5, 4]</span></span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a>lengths <span class="op">=</span> ____</span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb21-4"><a href="#cb21-4" tabindex="-1"></a>    lengths.____(____)</span>
+<span id="cb21-5"><a href="#cb21-5" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
 </div>
 </div>
 </div>
@@ -791,15 +791,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>lengths <span class="op">=</span> []</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb22-3"><a href="#cb22-3" aria-hidden="true" tabindex="-1"></a>    lengths.append(<span class="bu">len</span>(word))</span>
-<span id="cb22-4"><a href="#cb22-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>lengths <span class="op">=</span> []</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb22-3"><a href="#cb22-3" tabindex="-1"></a>    lengths.append(<span class="bu">len</span>(word))</span>
+<span id="cb22-4"><a href="#cb22-4" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
 </div>
 </div>
 </div>
@@ -816,12 +816,12 @@ <h3 class="callout-title">Practice Accumulating<em>(continued)</em><a class="anc
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Concatenate all words: ["red", "green", "blue"] =&gt; "redgreenblue"</span></span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
-<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> ____</span>
-<span id="cb23-4"><a href="#cb23-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> ____ <span class="kw">in</span> ____:</span>
-<span id="cb23-5"><a href="#cb23-5" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb23-6"><a href="#cb23-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="co"># Concatenate all words: ["red", "green", "blue"] =&gt; "redgreenblue"</span></span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
+<span id="cb23-3"><a href="#cb23-3" tabindex="-1"></a>result <span class="op">=</span> ____</span>
+<span id="cb23-4"><a href="#cb23-4" tabindex="-1"></a><span class="cf">for</span> ____ <span class="kw">in</span> ____:</span>
+<span id="cb23-5"><a href="#cb23-5" tabindex="-1"></a>    ____</span>
+<span id="cb23-6"><a href="#cb23-6" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -831,16 +831,16 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Show me the solution</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> words:</span>
-<span id="cb24-4"><a href="#cb24-4" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> result <span class="op">+</span> word</span>
-<span id="cb24-5"><a href="#cb24-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb24-3"><a href="#cb24-3" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> words:</span>
+<span id="cb24-4"><a href="#cb24-4" tabindex="-1"></a>    result <span class="op">=</span> result <span class="op">+</span> word</span>
+<span id="cb24-5"><a href="#cb24-5" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -867,15 +867,15 @@ <h3 class="callout-title">Practice Accumulating<em>(continued)</em><a class="anc
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a>acronym <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a>    acronym <span class="op">=</span> acronym <span class="op">+</span> word[<span class="dv">0</span>].upper()</span>
-<span id="cb25-4"><a href="#cb25-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(acronym)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a>acronym <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a>    acronym <span class="op">=</span> acronym <span class="op">+</span> word[<span class="dv">0</span>].upper()</span>
+<span id="cb25-4"><a href="#cb25-4" tabindex="-1"></a><span class="bu">print</span>(acronym)</span></code></pre>
 </div>
 </div>
 </div>
@@ -895,13 +895,13 @@ <h3 class="callout-title">Cumulative Sum<a class="anchor" aria-label="anchor" hr
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>cumulative.append(total)</span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
-<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> total <span class="op">+</span> number</span>
-<span id="cb26-5"><a href="#cb26-5" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb26-6"><a href="#cb26-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span>
-<span id="cb26-7"><a href="#cb26-7" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>cumulative.append(total)</span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
+<span id="cb26-4"><a href="#cb26-4" tabindex="-1"></a>total <span class="op">=</span> total <span class="op">+</span> number</span>
+<span id="cb26-5"><a href="#cb26-5" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb26-6"><a href="#cb26-6" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span>
+<span id="cb26-7"><a href="#cb26-7" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -911,18 +911,18 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Show me the solution</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span>
-<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
-<span id="cb27-4"><a href="#cb27-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
-<span id="cb27-5"><a href="#cb27-5" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> number</span>
-<span id="cb27-6"><a href="#cb27-6" aria-hidden="true" tabindex="-1"></a>    cumulative.append(total)</span>
-<span id="cb27-7"><a href="#cb27-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span>
+<span id="cb27-3"><a href="#cb27-3" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
+<span id="cb27-4"><a href="#cb27-4" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
+<span id="cb27-5"><a href="#cb27-5" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> number</span>
+<span id="cb27-6"><a href="#cb27-6" tabindex="-1"></a>    cumulative.append(total)</span>
+<span id="cb27-7"><a href="#cb27-7" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span></code></pre>
 </div>
 </div>
 </div>
@@ -947,13 +947,13 @@ <h3 class="callout-title">Identifying Variable Name Errors<a class="anchor" aria
 </ol><div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
-<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> (Number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb28-4"><a href="#cb28-4" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> a</span>
-<span id="cb28-5"><a href="#cb28-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb28-6"><a href="#cb28-6" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
-<span id="cb28-7"><a href="#cb28-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
+<span id="cb28-3"><a href="#cb28-3" tabindex="-1"></a>    <span class="cf">if</span> (Number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb28-4"><a href="#cb28-4" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> a</span>
+<span id="cb28-5"><a href="#cb28-5" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb28-6"><a href="#cb28-6" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
+<span id="cb28-7"><a href="#cb28-7" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
 </div>
 </div>
 </div>
@@ -963,7 +963,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution9" aria-expanded="false" aria-controls="collapseSolution9">
   <h4 class="accordion-header" id="headingSolution9">Show me the solution</h4>
 </button>
-<div id="collapseSolution9" class="accordion-collapse collapse" data-bs-parent="#accordionSolution9" aria-labelledby="headingSolution9">
+<div id="collapseSolution9" class="accordion-collapse collapse" aria-labelledby="headingSolution9" data-bs-parent="#accordionSolution9">
 <div class="accordion-body">
 <ul><li>Python variable names are case sensitive: <code>number</code> and
 <code>Number</code> refer to different variables.</li>
@@ -974,14 +974,14 @@ <h4 class="accordion-header" id="headingSolution9">Show me the solution</h4>
 </ul><div class="codewrapper sourceCode" id="cb29">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a>message <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
-<span id="cb29-4"><a href="#cb29-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> (number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb29-5"><a href="#cb29-5" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"a"</span></span>
-<span id="cb29-6"><a href="#cb29-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb29-7"><a href="#cb29-7" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
-<span id="cb29-8"><a href="#cb29-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" tabindex="-1"></a>message <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb29-2"><a href="#cb29-2" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb29-3"><a href="#cb29-3" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
+<span id="cb29-4"><a href="#cb29-4" tabindex="-1"></a>    <span class="cf">if</span> (number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb29-5"><a href="#cb29-5" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"a"</span></span>
+<span id="cb29-6"><a href="#cb29-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb29-7"><a href="#cb29-7" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
+<span id="cb29-8"><a href="#cb29-8" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
 </div>
 </div>
 </div>
@@ -1003,8 +1003,8 @@ <h3 class="callout-title">Identifying Item Errors<a class="anchor" aria-label="a
 </ol><div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
-<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">4</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
+<span id="cb30-2"><a href="#cb30-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">4</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -1014,15 +1014,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution10" aria-expanded="false" aria-controls="collapseSolution10">
   <h4 class="accordion-header" id="headingSolution10">Show me the solution</h4>
 </button>
-<div id="collapseSolution10" class="accordion-collapse collapse" data-bs-parent="#accordionSolution10" aria-labelledby="headingSolution10">
+<div id="collapseSolution10" class="accordion-collapse collapse" aria-labelledby="headingSolution10" data-bs-parent="#accordionSolution10">
 <div class="accordion-body">
 <p>This list has 4 elements and the index to access the last element in
 the list is <code>3</code>.</p>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">3</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -1110,7 +1110,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/12-for-loops.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/13-conditionals.html b/instructor/13-conditionals.html
index 00c1ad3a4..32c801867 100644
--- a/instructor/13-conditionals.html
+++ b/instructor/13-conditionals.html
@@ -445,13 +445,13 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">3.54</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(mass, <span class="st">'is large'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">2.07</span></span>
-<span id="cb1-6"><a href="#cb1-6" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb1-7"><a href="#cb1-7" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span> (mass, <span class="st">'is large'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">3.54</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    <span class="bu">print</span>(mass, <span class="st">'is large'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a></span>
+<span id="cb1-5"><a href="#cb1-5" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">2.07</span></span>
+<span id="cb1-6"><a href="#cb1-6" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb1-7"><a href="#cb1-7" tabindex="-1"></a>    <span class="bu">print</span> (mass, <span class="st">'is large'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -466,10 +466,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
-<span id="cb3-3"><a href="#cb3-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb3-4"><a href="#cb3-4" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
+<span id="cb3-3"><a href="#cb3-3" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb3-4"><a href="#cb3-4" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -487,12 +487,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb5-6"><a href="#cb5-6" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -515,14 +515,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">9.0</span>:</span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is HUGE'</span>)</span>
-<span id="cb7-5"><a href="#cb7-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb7-6"><a href="#cb7-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
-<span id="cb7-7"><a href="#cb7-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb7-8"><a href="#cb7-8" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">9.0</span>:</span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is HUGE'</span>)</span>
+<span id="cb7-5"><a href="#cb7-5" tabindex="-1"></a>    <span class="cf">elif</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb7-6"><a href="#cb7-6" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
+<span id="cb7-7"><a href="#cb7-7" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb7-8"><a href="#cb7-8" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -541,13 +541,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>grade <span class="op">=</span> <span class="dv">85</span></span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> grade <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is A'</span>)</span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">80</span>:</span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is B'</span>)</span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is C'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>grade <span class="op">=</span> <span class="dv">85</span></span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="cf">if</span> grade <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is A'</span>)</span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">80</span>:</span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is B'</span>)</span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is C'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -559,12 +559,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
-<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a><span class="cf">else</span>:</span>
-<span id="cb11-5"><a href="#cb11-5" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'adjusting velocity'</span>)</span>
-<span id="cb11-6"><a href="#cb11-6" aria-hidden="true" tabindex="-1"></a>    velocity <span class="op">=</span> <span class="fl">50.0</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
+<span id="cb11-4"><a href="#cb11-4" tabindex="-1"></a><span class="cf">else</span>:</span>
+<span id="cb11-5"><a href="#cb11-5" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'adjusting velocity'</span>)</span>
+<span id="cb11-6"><a href="#cb11-6" tabindex="-1"></a>    velocity <span class="op">=</span> <span class="fl">50.0</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -576,16 +576,16 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>): <span class="co"># execute the loop 5 times</span></span>
-<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(i, <span class="st">':'</span>, velocity)</span>
-<span id="cb13-4"><a href="#cb13-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
-<span id="cb13-5"><a href="#cb13-5" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
-<span id="cb13-6"><a href="#cb13-6" aria-hidden="true" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">-</span> <span class="fl">5.0</span></span>
-<span id="cb13-7"><a href="#cb13-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb13-8"><a href="#cb13-8" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too slow'</span>)</span>
-<span id="cb13-9"><a href="#cb13-9" aria-hidden="true" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">+</span> <span class="fl">10.0</span></span>
-<span id="cb13-10"><a href="#cb13-10" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'final velocity:'</span>, velocity)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>): <span class="co"># execute the loop 5 times</span></span>
+<span id="cb13-3"><a href="#cb13-3" tabindex="-1"></a>    <span class="bu">print</span>(i, <span class="st">':'</span>, velocity)</span>
+<span id="cb13-4"><a href="#cb13-4" tabindex="-1"></a>    <span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
+<span id="cb13-5"><a href="#cb13-5" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
+<span id="cb13-6"><a href="#cb13-6" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">-</span> <span class="fl">5.0</span></span>
+<span id="cb13-7"><a href="#cb13-7" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb13-8"><a href="#cb13-8" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too slow'</span>)</span>
+<span id="cb13-9"><a href="#cb13-9" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">+</span> <span class="fl">10.0</span></span>
+<span id="cb13-10"><a href="#cb13-10" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'final velocity:'</span>, velocity)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -675,13 +675,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <em>outside</em> the body of the loop to show the final value of
 <code>velocity</code>, since its value is updated by the last iteration
 of the loop.</li>
-</ul><div id="compound-relations-using-and-or-and-parentheses" class="callout callout">
+</ul><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="compound-relations-using-and-or-and-parentheses" class="callout-inner">
-<h3 class="callout-title">Compound Relations Using<code>and</code>,<code>or</code>, and Parentheses<a class="anchor" aria-label="anchor" href="#compound-relations-using-and-or-and-parentheses"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="compound-relations-using-and-or-and-parentheses">Compound Relations Using <code>and</code>,
+<code>or</code>, and Parentheses<a class="anchor" aria-label="anchor" href="#compound-relations-using-and-or-and-parentheses"></a></h3>
 <div class="callout-content">
 <p>Often, you want some combination of things to be true. You can
 combine relations within a conditional using <code>and</code> and
@@ -689,19 +689,19 @@ <h3 class="callout-title">Compound Relations Using<code>and</code>,<code>or</cod
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>mass     <span class="op">=</span> [ <span class="fl">3.54</span>,  <span class="fl">2.07</span>,  <span class="fl">9.22</span>,  <span class="fl">1.86</span>,  <span class="fl">1.71</span>]</span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>velocity <span class="op">=</span> [<span class="fl">10.00</span>, <span class="fl">20.00</span>, <span class="fl">30.00</span>, <span class="fl">25.00</span>, <span class="fl">20.00</span>]</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>):</span>
-<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> mass[i] <span class="op">&gt;</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
-<span id="cb15-7"><a href="#cb15-7" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Fast heavy object.  Duck!"</span>)</span>
-<span id="cb15-8"><a href="#cb15-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&gt;</span> <span class="dv">2</span> <span class="kw">and</span> mass[i] <span class="op">&lt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
-<span id="cb15-9"><a href="#cb15-9" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Normal traffic"</span>)</span>
-<span id="cb15-10"><a href="#cb15-10" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
-<span id="cb15-11"><a href="#cb15-11" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Slow light object.  Ignore it"</span>)</span>
-<span id="cb15-12"><a href="#cb15-12" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb15-13"><a href="#cb15-13" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Whoa!  Something is up with the data.  Check it"</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a>mass     <span class="op">=</span> [ <span class="fl">3.54</span>,  <span class="fl">2.07</span>,  <span class="fl">9.22</span>,  <span class="fl">1.86</span>,  <span class="fl">1.71</span>]</span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>velocity <span class="op">=</span> [<span class="fl">10.00</span>, <span class="fl">20.00</span>, <span class="fl">30.00</span>, <span class="fl">25.00</span>, <span class="fl">20.00</span>]</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a></span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb15-5"><a href="#cb15-5" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>):</span>
+<span id="cb15-6"><a href="#cb15-6" tabindex="-1"></a>    <span class="cf">if</span> mass[i] <span class="op">&gt;</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
+<span id="cb15-7"><a href="#cb15-7" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Fast heavy object.  Duck!"</span>)</span>
+<span id="cb15-8"><a href="#cb15-8" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&gt;</span> <span class="dv">2</span> <span class="kw">and</span> mass[i] <span class="op">&lt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
+<span id="cb15-9"><a href="#cb15-9" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Normal traffic"</span>)</span>
+<span id="cb15-10"><a href="#cb15-10" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
+<span id="cb15-11"><a href="#cb15-11" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Slow light object.  Ignore it"</span>)</span>
+<span id="cb15-12"><a href="#cb15-12" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb15-13"><a href="#cb15-13" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Whoa!  Something is up with the data.  Check it"</span>)</span></code></pre>
 </div>
 <p>Just like with arithmetic, you can and should use parentheses
 whenever there is possible ambiguity. A good general rule is to
@@ -710,14 +710,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span></code></pre>
 </div>
 <p>write one of these:</p>
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> (mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span>) <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> (mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>):</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="cf">if</span> (mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span>) <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> (mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>):</span></code></pre>
 </div>
 <p>so it is perfectly clear to a reader (and to Python) what you really
 mean.</p>
@@ -736,12 +736,12 @@ <h3 class="callout-title">Tracing Execution<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">71.9</span></span>
-<span id="cb18-2"><a href="#cb18-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> pressure <span class="op">&gt;</span> <span class="fl">50.0</span>:</span>
-<span id="cb18-3"><a href="#cb18-3" aria-hidden="true" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">25.0</span></span>
-<span id="cb18-4"><a href="#cb18-4" aria-hidden="true" tabindex="-1"></a><span class="cf">elif</span> pressure <span class="op">&lt;=</span> <span class="fl">50.0</span>:</span>
-<span id="cb18-5"><a href="#cb18-5" aria-hidden="true" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">0.0</span></span>
-<span id="cb18-6"><a href="#cb18-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(pressure)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">71.9</span></span>
+<span id="cb18-2"><a href="#cb18-2" tabindex="-1"></a><span class="cf">if</span> pressure <span class="op">&gt;</span> <span class="fl">50.0</span>:</span>
+<span id="cb18-3"><a href="#cb18-3" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">25.0</span></span>
+<span id="cb18-4"><a href="#cb18-4" tabindex="-1"></a><span class="cf">elif</span> pressure <span class="op">&lt;=</span> <span class="fl">50.0</span>:</span>
+<span id="cb18-5"><a href="#cb18-5" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">0.0</span></span>
+<span id="cb18-6"><a href="#cb18-6" tabindex="-1"></a><span class="bu">print</span>(pressure)</span></code></pre>
 </div>
 </div>
 </div>
@@ -776,14 +776,14 @@ <h3 class="callout-title">Trimming Values<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> ____</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
-<span id="cb20-4"><a href="#cb20-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
-<span id="cb20-5"><a href="#cb20-5" aria-hidden="true" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
-<span id="cb20-6"><a href="#cb20-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb20-7"><a href="#cb20-7" aria-hidden="true" tabindex="-1"></a>        ____</span>
-<span id="cb20-8"><a href="#cb20-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>result <span class="op">=</span> ____</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
+<span id="cb20-4"><a href="#cb20-4" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
+<span id="cb20-5"><a href="#cb20-5" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
+<span id="cb20-6"><a href="#cb20-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb20-7"><a href="#cb20-7" tabindex="-1"></a>        ____</span>
+<span id="cb20-8"><a href="#cb20-8" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -803,14 +803,14 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> []</span>
-<span id="cb22-3"><a href="#cb22-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
-<span id="cb22-4"><a href="#cb22-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> value <span class="op">&lt;</span> <span class="fl">0.0</span>:</span>
-<span id="cb22-5"><a href="#cb22-5" aria-hidden="true" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
-<span id="cb22-6"><a href="#cb22-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb22-7"><a href="#cb22-7" aria-hidden="true" tabindex="-1"></a>        result.append(<span class="dv">1</span>)</span>
-<span id="cb22-8"><a href="#cb22-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>result <span class="op">=</span> []</span>
+<span id="cb22-3"><a href="#cb22-3" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
+<span id="cb22-4"><a href="#cb22-4" tabindex="-1"></a>    <span class="cf">if</span> value <span class="op">&lt;</span> <span class="fl">0.0</span>:</span>
+<span id="cb22-5"><a href="#cb22-5" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
+<span id="cb22-6"><a href="#cb22-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb22-7"><a href="#cb22-7" tabindex="-1"></a>        result.append(<span class="dv">1</span>)</span>
+<span id="cb22-8"><a href="#cb22-8" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -829,12 +829,12 @@ <h3 class="callout-title">Processing Small Files<a class="anchor" aria-label="an
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb23-4"><a href="#cb23-4" aria-hidden="true" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb23-5"><a href="#cb23-5" aria-hidden="true" tabindex="-1"></a>    ____:</span>
-<span id="cb23-6"><a href="#cb23-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb23-3"><a href="#cb23-3" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb23-4"><a href="#cb23-4" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb23-5"><a href="#cb23-5" tabindex="-1"></a>    ____:</span>
+<span id="cb23-6"><a href="#cb23-6" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
 </div>
 </div>
 </div>
@@ -849,12 +849,12 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb24-4"><a href="#cb24-4" aria-hidden="true" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb24-5"><a href="#cb24-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(contents) <span class="op">&lt;</span> <span class="dv">50</span>:</span>
-<span id="cb24-6"><a href="#cb24-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb24-3"><a href="#cb24-3" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb24-4"><a href="#cb24-4" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb24-5"><a href="#cb24-5" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(contents) <span class="op">&lt;</span> <span class="dv">50</span>:</span>
+<span id="cb24-6"><a href="#cb24-6" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
 </div>
 </div>
 </div>
@@ -873,15 +873,15 @@ <h3 class="callout-title">Initializing<a class="anchor" aria-label="anchor" href
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [...some test data...]</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb25-4"><a href="#cb25-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
-<span id="cb25-5"><a href="#cb25-5" aria-hidden="true" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
-<span id="cb25-6"><a href="#cb25-6" aria-hidden="true" tabindex="-1"></a>    ____:</span>
-<span id="cb25-7"><a href="#cb25-7" aria-hidden="true" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(____, v)</span>
-<span id="cb25-8"><a href="#cb25-8" aria-hidden="true" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(____, v)</span>
-<span id="cb25-9"><a href="#cb25-9" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a>values <span class="op">=</span> [...some test data...]</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb25-4"><a href="#cb25-4" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
+<span id="cb25-5"><a href="#cb25-5" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
+<span id="cb25-6"><a href="#cb25-6" tabindex="-1"></a>    ____:</span>
+<span id="cb25-7"><a href="#cb25-7" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(____, v)</span>
+<span id="cb25-8"><a href="#cb25-8" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(____, v)</span>
+<span id="cb25-9"><a href="#cb25-9" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 <p>What are the advantages and disadvantages of using this method to
 find the range of the data?</p>
@@ -898,15 +898,15 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">and</span> largest <span class="kw">is</span> <span class="va">None</span>:</span>
-<span id="cb26-5"><a href="#cb26-5" aria-hidden="true" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
-<span id="cb26-6"><a href="#cb26-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb26-7"><a href="#cb26-7" aria-hidden="true" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(smallest, v)</span>
-<span id="cb26-8"><a href="#cb26-8" aria-hidden="true" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(largest, v)</span>
-<span id="cb26-9"><a href="#cb26-9" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb26-4"><a href="#cb26-4" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">and</span> largest <span class="kw">is</span> <span class="va">None</span>:</span>
+<span id="cb26-5"><a href="#cb26-5" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
+<span id="cb26-6"><a href="#cb26-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb26-7"><a href="#cb26-7" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(smallest, v)</span>
+<span id="cb26-8"><a href="#cb26-8" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(largest, v)</span>
+<span id="cb26-9"><a href="#cb26-9" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 <p>If you wrote <code>== None</code> instead of <code>is None</code>,
 that works too, but Python programmers always write <code>is None</code>
@@ -920,14 +920,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
-<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb27-4"><a href="#cb27-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&lt;</span> smallest:</span>
-<span id="cb27-5"><a href="#cb27-5" aria-hidden="true" tabindex="-1"></a>        smallest <span class="op">=</span> v</span>
-<span id="cb27-6"><a href="#cb27-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> largest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&gt;</span> largest:</span>
-<span id="cb27-7"><a href="#cb27-7" aria-hidden="true" tabindex="-1"></a>        largest <span class="op">=</span> v</span>
-<span id="cb27-8"><a href="#cb27-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
+<span id="cb27-3"><a href="#cb27-3" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb27-4"><a href="#cb27-4" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&lt;</span> smallest:</span>
+<span id="cb27-5"><a href="#cb27-5" tabindex="-1"></a>        smallest <span class="op">=</span> v</span>
+<span id="cb27-6"><a href="#cb27-6" tabindex="-1"></a>    <span class="cf">if</span> largest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&gt;</span> largest:</span>
+<span id="cb27-7"><a href="#cb27-7" tabindex="-1"></a>        largest <span class="op">=</span> v</span>
+<span id="cb27-8"><a href="#cb27-8" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 <p>Now we have one loop, but four comparison tests. There are two ways
 we could improve it further: either use fewer comparisons in each
@@ -936,10 +936,10 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a>smallest <span class="op">=</span> <span class="bu">min</span>(values)</span>
-<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a>largest <span class="op">=</span> <span class="bu">max</span>(values)</span>
-<span id="cb28-4"><a href="#cb28-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a>smallest <span class="op">=</span> <span class="bu">min</span>(values)</span>
+<span id="cb28-3"><a href="#cb28-3" tabindex="-1"></a>largest <span class="op">=</span> <span class="bu">max</span>(values)</span>
+<span id="cb28-4"><a href="#cb28-4" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 </div>
 </div>
@@ -1024,7 +1024,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/13-conditionals.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2024-02-16",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/14-looping-data-sets.html b/instructor/14-looping-data-sets.html
index b466ce455..85cf59905 100644
--- a/instructor/14-looping-data-sets.html
+++ b/instructor/14-looping-data-sets.html
@@ -437,10 +437,10 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> [<span class="st">'data/gapminder_gdp_africa.csv'</span>, <span class="st">'data/gapminder_gdp_asia.csv'</span>]:</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(filename, data.<span class="bu">min</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> [<span class="st">'data/gapminder_gdp_africa.csv'</span>, <span class="st">'data/gapminder_gdp_asia.csv'</span>]:</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    <span class="bu">print</span>(filename, data.<span class="bu">min</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -486,8 +486,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all csv files in data directory:'</span>, glob.glob(<span class="st">'data/*.csv'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all csv files in data directory:'</span>, glob.glob(<span class="st">'data/*.csv'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -499,7 +499,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all PDB files:'</span>, glob.glob(<span class="st">'*.pdb'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all PDB files:'</span>, glob.glob(<span class="st">'*.pdb'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -514,9 +514,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_*.csv'</span>):</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(filename, data[<span class="st">'gdpPercap_1952'</span>].<span class="bu">min</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_*.csv'</span>):</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a>    <span class="bu">print</span>(filename, data[<span class="st">'gdpPercap_1952'</span>].<span class="bu">min</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -554,7 +554,7 @@ <h3 class="callout-title">Determining Matches<a class="anchor" aria-label="ancho
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>1 is not matched by the glob.</p>
 </div>
@@ -574,13 +574,13 @@ <h3 class="callout-title">Minimum File Size<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a>fewest <span class="op">=</span> ____</span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.____(filename)</span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(____, dataframe.shape[<span class="dv">0</span>])</span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a>fewest <span class="op">=</span> ____</span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.____(filename)</span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(____, dataframe.shape[<span class="dv">0</span>])</span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
 </div>
 <p>Note that the <a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.shape.html" class="external-link"><code>DataFrame.shape()</code>
 method</a> returns a tuple with the number of rows and columns of the
@@ -593,18 +593,18 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>fewest <span class="op">=</span> <span class="bu">float</span>(<span class="st">'Inf'</span>)</span>
-<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb10-5"><a href="#cb10-5" aria-hidden="true" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb10-6"><a href="#cb10-6" aria-hidden="true" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(fewest, dataframe.shape[<span class="dv">0</span>])</span>
-<span id="cb10-7"><a href="#cb10-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb10-3"><a href="#cb10-3" tabindex="-1"></a>fewest <span class="op">=</span> <span class="bu">float</span>(<span class="st">'Inf'</span>)</span>
+<span id="cb10-4"><a href="#cb10-4" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb10-5"><a href="#cb10-5" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb10-6"><a href="#cb10-6" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(fewest, dataframe.shape[<span class="dv">0</span>])</span>
+<span id="cb10-7"><a href="#cb10-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
 </div>
 <p>You might have chosen to initialize the <code>fewest</code> variable
 with a number greater than the numbers you’re dealing with, but that
@@ -634,7 +634,7 @@ <h3 class="callout-title">Comparing Data<a class="anchor" aria-label="anchor" hr
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>This solution builds a useful legend by using the <a href="https://docs.python.org/3/library/stdtypes.html#str.split" class="external-link">string
 <code>split</code> method</a> to extract the <code>region</code> from
@@ -642,32 +642,31 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span>
-<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a>fig, ax <span class="op">=</span> plt.subplots(<span class="dv">1</span>,<span class="dv">1</span>)</span>
-<span id="cb11-5"><a href="#cb11-5" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_gdp*.csv'</span>):</span>
-<span id="cb11-6"><a href="#cb11-6" aria-hidden="true" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb11-7"><a href="#cb11-7" aria-hidden="true" tabindex="-1"></a>    <span class="co"># extract &lt;region&gt; from the filename, expected to be in the format 'data/gapminder_gdp_&lt;region&gt;.csv'.</span></span>
-<span id="cb11-8"><a href="#cb11-8" aria-hidden="true" tabindex="-1"></a>    <span class="co"># we will split the string using the split method and `_` as our separator,</span></span>
-<span id="cb11-9"><a href="#cb11-9" aria-hidden="true" tabindex="-1"></a>    <span class="co"># retrieve the last string in the list that split returns (`&lt;region&gt;.csv`), </span></span>
-<span id="cb11-10"><a href="#cb11-10" aria-hidden="true" tabindex="-1"></a>    <span class="co"># and then remove the `.csv` extension from that string.</span></span>
-<span id="cb11-11"><a href="#cb11-11" aria-hidden="true" tabindex="-1"></a>    region <span class="op">=</span> filename.split(<span class="st">'_'</span>)[<span class="op">-</span><span class="dv">1</span>][:<span class="op">-</span><span class="dv">4</span>] </span>
-<span id="cb11-12"><a href="#cb11-12" aria-hidden="true" tabindex="-1"></a>    dataframe.mean().plot(ax<span class="op">=</span>ax, label<span class="op">=</span>region)</span>
-<span id="cb11-13"><a href="#cb11-13" aria-hidden="true" tabindex="-1"></a>plt.legend()</span>
-<span id="cb11-14"><a href="#cb11-14" aria-hidden="true" tabindex="-1"></a>plt.show()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span>
+<span id="cb11-4"><a href="#cb11-4" tabindex="-1"></a>fig, ax <span class="op">=</span> plt.subplots(<span class="dv">1</span>,<span class="dv">1</span>)</span>
+<span id="cb11-5"><a href="#cb11-5" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_gdp*.csv'</span>):</span>
+<span id="cb11-6"><a href="#cb11-6" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb11-7"><a href="#cb11-7" tabindex="-1"></a>    <span class="co"># extract &lt;region&gt; from the filename, expected to be in the format 'data/gapminder_gdp_&lt;region&gt;.csv'.</span></span>
+<span id="cb11-8"><a href="#cb11-8" tabindex="-1"></a>    <span class="co"># we will split the string using the split method and `_` as our separator,</span></span>
+<span id="cb11-9"><a href="#cb11-9" tabindex="-1"></a>    <span class="co"># retrieve the last string in the list that split returns (`&lt;region&gt;.csv`), </span></span>
+<span id="cb11-10"><a href="#cb11-10" tabindex="-1"></a>    <span class="co"># and then remove the `.csv` extension from that string.</span></span>
+<span id="cb11-11"><a href="#cb11-11" tabindex="-1"></a>    region <span class="op">=</span> filename.split(<span class="st">'_'</span>)[<span class="op">-</span><span class="dv">1</span>][:<span class="op">-</span><span class="dv">4</span>] </span>
+<span id="cb11-12"><a href="#cb11-12" tabindex="-1"></a>    dataframe.mean().plot(ax<span class="op">=</span>ax, label<span class="op">=</span>region)</span>
+<span id="cb11-13"><a href="#cb11-13" tabindex="-1"></a>plt.legend()</span>
+<span id="cb11-14"><a href="#cb11-14" tabindex="-1"></a>plt.show()</span></code></pre>
 </div>
 </div>
 </div>
 </div>
 </div>
-<div id="dealing-with-file-paths" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="dealing-with-file-paths" class="callout-inner">
-<h3 class="callout-title">Dealing with File Paths<a class="anchor" aria-label="anchor" href="#dealing-with-file-paths"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="dealing-with-file-paths">Dealing with File Paths<a class="anchor" aria-label="anchor" href="#dealing-with-file-paths"></a></h3>
 <div class="callout-content">
 <p>The <a href="https://docs.python.org/3/library/pathlib.html" class="external-link"><code>pathlib</code>
 module</a> provides useful abstractions for file and path manipulation
@@ -678,10 +677,10 @@ <h3 class="callout-title">Dealing with File Paths<a class="anchor" aria-label="a
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> pathlib <span class="im">import</span> Path</span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a>p <span class="op">=</span> Path(<span class="st">"data/gapminder_gdp_africa.csv"</span>)</span>
-<span id="cb12-4"><a href="#cb12-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(p.parent), <span class="bu">print</span>(p.stem), <span class="bu">print</span>(p.suffix)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="im">from</span> pathlib <span class="im">import</span> Path</span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a></span>
+<span id="cb12-3"><a href="#cb12-3" tabindex="-1"></a>p <span class="op">=</span> Path(<span class="st">"data/gapminder_gdp_africa.csv"</span>)</span>
+<span id="cb12-4"><a href="#cb12-4" tabindex="-1"></a><span class="bu">print</span>(p.parent), <span class="bu">print</span>(p.stem), <span class="bu">print</span>(p.suffix)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -772,7 +771,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/14-looping-data-sets.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/15-coffee.html b/instructor/15-coffee.html
index d7d198989..fda41ef28 100644
--- a/instructor/15-coffee.html
+++ b/instructor/15-coffee.html
@@ -470,7 +470,7 @@ <h1>Afternoon Coffee</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/15-coffee.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/16-writing-functions.html b/instructor/16-writing-functions.html
index 51c8dd6d0..184a1307e 100644
--- a/instructor/16-writing-functions.html
+++ b/instructor/16-writing-functions.html
@@ -465,10 +465,10 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_greeting():</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Hello!'</span>)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'The weather is nice today.'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Right?'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="kw">def</span> print_greeting():</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Hello!'</span>)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'The weather is nice today.'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Right?'</span>)</span></code></pre>
 </div>
 </section><section id="defining-a-function-does-not-run-it."><h2 class="section-heading">Defining a function does not run it.<a class="anchor" aria-label="anchor" href="#defining-a-function-does-not-run-it."></a>
 </h2>
@@ -479,7 +479,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a>print_greeting()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a>print_greeting()</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -502,11 +502,11 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-5"><a href="#cb4-5" aria-hidden="true" tabindex="-1"></a>print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
+<span id="cb4-3"><a href="#cb4-3" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span>
+<span id="cb4-4"><a href="#cb4-4" tabindex="-1"></a></span>
+<span id="cb4-5"><a href="#cb4-5" tabindex="-1"></a>print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -520,7 +520,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>print_date(month<span class="op">=</span><span class="dv">3</span>, day<span class="op">=</span><span class="dv">19</span>, year<span class="op">=</span><span class="dv">1871</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a>print_date(month<span class="op">=</span><span class="dv">3</span>, day<span class="op">=</span><span class="dv">19</span>, year<span class="op">=</span><span class="dv">1871</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -543,16 +543,16 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
-<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb8-3"><a href="#cb8-3" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
+<span id="cb8-4"><a href="#cb8-4" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">=</span> average([<span class="dv">1</span>, <span class="dv">3</span>, <span class="dv">4</span>])</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of actual values:'</span>, a)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>a <span class="op">=</span> average([<span class="dv">1</span>, <span class="dv">3</span>, <span class="dv">4</span>])</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of actual values:'</span>, a)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -562,7 +562,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of empty list:'</span>, average([]))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of empty list:'</span>, average([]))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -576,8 +576,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>result <span class="op">=</span> print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -602,10 +602,10 @@ <h3 class="callout-title">Identifying Syntax Errors<a class="anchor" aria-label=
 </ol><div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> another_function</span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a>   <span class="bu">print</span>(<span class="st">"But at least python tells us about them!"</span>)</span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="kw">def</span> another_function</span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a>   <span class="bu">print</span>(<span class="st">"But at least python tells us about them!"</span>)</span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -620,10 +620,10 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> another_function():</span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"But at least Python tells us about them!"</span>)</span>
-<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a><span class="kw">def</span> another_function():</span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"But at least Python tells us about them!"</span>)</span>
+<span id="cb16-4"><a href="#cb16-4" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -641,10 +641,10 @@ <h3 class="callout-title">Definition and Use<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> report(pressure):</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'pressure is'</span>, pressure)</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'calling'</span>, report, <span class="fl">22.5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="kw">def</span> report(pressure):</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'pressure is'</span>, pressure)</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a></span>
+<span id="cb17-4"><a href="#cb17-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'calling'</span>, report, <span class="fl">22.5</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -668,8 +668,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"calling"</span>)</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>report(<span class="fl">22.5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"calling"</span>)</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>report(<span class="fl">22.5</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -693,19 +693,19 @@ <h3 class="callout-title">Order of Operations<a class="anchor" aria-label="ancho
 </ol><div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_time(hour, minute, second):</span>
-<span id="cb21-4"><a href="#cb21-4" aria-hidden="true" tabindex="-1"></a>   time_string <span class="op">=</span> <span class="bu">str</span>(hour) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(minute) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(second)</span>
-<span id="cb21-5"><a href="#cb21-5" aria-hidden="true" tabindex="-1"></a>   <span class="bu">print</span>(time_string)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a></span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="kw">def</span> print_time(hour, minute, second):</span>
+<span id="cb21-4"><a href="#cb21-4" tabindex="-1"></a>   time_string <span class="op">=</span> <span class="bu">str</span>(hour) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(minute) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(second)</span>
+<span id="cb21-5"><a href="#cb21-5" tabindex="-1"></a>   <span class="bu">print</span>(time_string)</span></code></pre>
 </div>
 <ol start="2" style="list-style-type: decimal"><li>After fixing the problem above, explain why running this example
 code:</li>
 </ol><div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
 </div>
 <p>gives this output:</p>
 <div class="codewrapper">
@@ -756,11 +756,11 @@ <h3 class="callout-title">Encapsulation<a class="anchor" aria-label="anchor" hre
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> min_in_data(____):</span>
-<span id="cb24-4"><a href="#cb24-4" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> ____</span>
-<span id="cb24-5"><a href="#cb24-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> ____</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a></span>
+<span id="cb24-3"><a href="#cb24-3" tabindex="-1"></a><span class="kw">def</span> min_in_data(____):</span>
+<span id="cb24-4"><a href="#cb24-4" tabindex="-1"></a>    data <span class="op">=</span> ____</span>
+<span id="cb24-5"><a href="#cb24-5" tabindex="-1"></a>    <span class="cf">return</span> ____</span></code></pre>
 </div>
 </div>
 </div>
@@ -775,11 +775,11 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> min_in_data(filename):</span>
-<span id="cb25-4"><a href="#cb25-4" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb25-5"><a href="#cb25-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> data.<span class="bu">min</span>()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a></span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a><span class="kw">def</span> min_in_data(filename):</span>
+<span id="cb25-4"><a href="#cb25-4" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb25-5"><a href="#cb25-5" tabindex="-1"></a>    <span class="cf">return</span> data.<span class="bu">min</span>()</span></code></pre>
 </div>
 </div>
 </div>
@@ -800,10 +800,10 @@ <h3 class="callout-title">Find the First<a class="anchor" aria-label="anchor" hr
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> ____:</span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> ____:</span>
-<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a>            <span class="cf">return</span> ____</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> ____:</span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a>        <span class="cf">if</span> ____:</span>
+<span id="cb26-4"><a href="#cb26-4" tabindex="-1"></a>            <span class="cf">return</span> ____</span></code></pre>
 </div>
 </div>
 </div>
@@ -818,18 +818,18 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> v <span class="op">&lt;</span> <span class="dv">0</span>:</span>
-<span id="cb27-4"><a href="#cb27-4" aria-hidden="true" tabindex="-1"></a>            <span class="cf">return</span> v</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb27-3"><a href="#cb27-3" tabindex="-1"></a>        <span class="cf">if</span> v <span class="op">&lt;</span> <span class="dv">0</span>:</span>
+<span id="cb27-4"><a href="#cb27-4" tabindex="-1"></a>            <span class="cf">return</span> v</span></code></pre>
 </div>
 <p>If an empty list or a list with all positive values is passed to this
 function, it returns <code>None</code>:</p>
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>my_list <span class="op">=</span> []</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(first_negative(my_list))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>my_list <span class="op">=</span> []</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a><span class="bu">print</span>(first_negative(my_list))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -852,16 +852,16 @@ <h3 class="callout-title">Calling by Name<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
-<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
-<span id="cb30-3"><a href="#cb30-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
+<span id="cb30-2"><a href="#cb30-2" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
+<span id="cb30-3"><a href="#cb30-3" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span></code></pre>
 </div>
 <p>We saw that we can call the function using <em>named arguments</em>,
 like this:</p>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>print_date(day<span class="op">=</span><span class="dv">1</span>, month<span class="op">=</span><span class="dv">2</span>, year<span class="op">=</span><span class="dv">2003</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>print_date(day<span class="op">=</span><span class="dv">1</span>, month<span class="op">=</span><span class="dv">2</span>, year<span class="op">=</span><span class="dv">2003</span>)</span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>What does <code>print_date(day=1, month=2, year=2003)</code>
 print?</li>
@@ -905,24 +905,24 @@ <h3 class="callout-title">Encapsulation of an If/Print Block<a class="anchor" ar
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb32-2"><a href="#cb32-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb32-3"><a href="#cb32-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb32-4"><a href="#cb32-4" aria-hidden="true" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
-<span id="cb32-5"><a href="#cb32-5" aria-hidden="true" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
-<span id="cb32-6"><a href="#cb32-6" aria-hidden="true" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
-<span id="cb32-7"><a href="#cb32-7" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb32-8"><a href="#cb32-8" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(mass)</span>
-<span id="cb32-9"><a href="#cb32-9" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb32-10"><a href="#cb32-10" aria-hidden="true" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
-<span id="cb32-11"><a href="#cb32-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
-<span id="cb32-12"><a href="#cb32-12" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"jumbo"</span>)</span>
-<span id="cb32-13"><a href="#cb32-13" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
-<span id="cb32-14"><a href="#cb32-14" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"large"</span>)</span>
-<span id="cb32-15"><a href="#cb32-15" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
-<span id="cb32-16"><a href="#cb32-16" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"medium"</span>)</span>
-<span id="cb32-17"><a href="#cb32-17" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb32-18"><a href="#cb32-18" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"small"</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb32-2"><a href="#cb32-2" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb32-3"><a href="#cb32-3" tabindex="-1"></a></span>
+<span id="cb32-4"><a href="#cb32-4" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
+<span id="cb32-5"><a href="#cb32-5" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
+<span id="cb32-6"><a href="#cb32-6" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
+<span id="cb32-7"><a href="#cb32-7" tabindex="-1"></a></span>
+<span id="cb32-8"><a href="#cb32-8" tabindex="-1"></a>    <span class="bu">print</span>(mass)</span>
+<span id="cb32-9"><a href="#cb32-9" tabindex="-1"></a></span>
+<span id="cb32-10"><a href="#cb32-10" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
+<span id="cb32-11"><a href="#cb32-11" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
+<span id="cb32-12"><a href="#cb32-12" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"jumbo"</span>)</span>
+<span id="cb32-13"><a href="#cb32-13" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
+<span id="cb32-14"><a href="#cb32-14" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"large"</span>)</span>
+<span id="cb32-15"><a href="#cb32-15" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
+<span id="cb32-16"><a href="#cb32-16" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"medium"</span>)</span>
+<span id="cb32-17"><a href="#cb32-17" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb32-18"><a href="#cb32-18" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"small"</span>)</span></code></pre>
 </div>
 <p>The if-block that classifies the eggs might be useful in other
 situations, so to avoid repeating it, we could fold it into a function,
@@ -931,15 +931,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb33">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a><span class="co"># revised version</span></span>
-<span id="cb33-2"><a href="#cb33-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb33-3"><a href="#cb33-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb33-4"><a href="#cb33-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb33-5"><a href="#cb33-5" aria-hidden="true" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
-<span id="cb33-6"><a href="#cb33-6" aria-hidden="true" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
-<span id="cb33-7"><a href="#cb33-7" aria-hidden="true" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
-<span id="cb33-8"><a href="#cb33-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb33-9"><a href="#cb33-9" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(mass, get_egg_label(mass))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" tabindex="-1"></a><span class="co"># revised version</span></span>
+<span id="cb33-2"><a href="#cb33-2" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb33-3"><a href="#cb33-3" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb33-4"><a href="#cb33-4" tabindex="-1"></a></span>
+<span id="cb33-5"><a href="#cb33-5" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
+<span id="cb33-6"><a href="#cb33-6" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
+<span id="cb33-7"><a href="#cb33-7" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
+<span id="cb33-8"><a href="#cb33-8" tabindex="-1"></a></span>
+<span id="cb33-9"><a href="#cb33-9" tabindex="-1"></a>    <span class="bu">print</span>(mass, get_egg_label(mass))</span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>Create a function definition for <code>get_egg_label()</code> that
 will work with the revised program above. Note that the
@@ -964,22 +964,22 @@ <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> get_egg_label(mass):</span>
-<span id="cb34-2"><a href="#cb34-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
-<span id="cb34-3"><a href="#cb34-3" aria-hidden="true" tabindex="-1"></a>    egg_label <span class="op">=</span> <span class="st">"Unlabelled"</span></span>
-<span id="cb34-4"><a href="#cb34-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
-<span id="cb34-5"><a href="#cb34-5" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"warning: egg might be dirty"</span></span>
-<span id="cb34-6"><a href="#cb34-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
-<span id="cb34-7"><a href="#cb34-7" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"jumbo"</span></span>
-<span id="cb34-8"><a href="#cb34-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
-<span id="cb34-9"><a href="#cb34-9" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"large"</span></span>
-<span id="cb34-10"><a href="#cb34-10" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
-<span id="cb34-11"><a href="#cb34-11" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"medium"</span></span>
-<span id="cb34-12"><a href="#cb34-12" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">50</span>:</span>
-<span id="cb34-13"><a href="#cb34-13" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"too light, probably spoiled"</span></span>
-<span id="cb34-14"><a href="#cb34-14" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb34-15"><a href="#cb34-15" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"small"</span></span>
-<span id="cb34-16"><a href="#cb34-16" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> egg_label</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a><span class="kw">def</span> get_egg_label(mass):</span>
+<span id="cb34-2"><a href="#cb34-2" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
+<span id="cb34-3"><a href="#cb34-3" tabindex="-1"></a>    egg_label <span class="op">=</span> <span class="st">"Unlabelled"</span></span>
+<span id="cb34-4"><a href="#cb34-4" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
+<span id="cb34-5"><a href="#cb34-5" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"warning: egg might be dirty"</span></span>
+<span id="cb34-6"><a href="#cb34-6" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
+<span id="cb34-7"><a href="#cb34-7" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"jumbo"</span></span>
+<span id="cb34-8"><a href="#cb34-8" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
+<span id="cb34-9"><a href="#cb34-9" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"large"</span></span>
+<span id="cb34-10"><a href="#cb34-10" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
+<span id="cb34-11"><a href="#cb34-11" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"medium"</span></span>
+<span id="cb34-12"><a href="#cb34-12" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">50</span>:</span>
+<span id="cb34-13"><a href="#cb34-13" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"too light, probably spoiled"</span></span>
+<span id="cb34-14"><a href="#cb34-14" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb34-15"><a href="#cb34-15" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"small"</span></span>
+<span id="cb34-16"><a href="#cb34-16" tabindex="-1"></a>    <span class="cf">return</span> egg_label</span></code></pre>
 </div>
 </div>
 </div>
@@ -997,30 +997,30 @@ <h3 class="callout-title">Encapsulating Data Analysis<a class="anchor" aria-labe
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb35-2"><a href="#cb35-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb35-3"><a href="#cb35-3" aria-hidden="true" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb35-4"><a href="#cb35-4" aria-hidden="true" tabindex="-1"></a>japan <span class="op">=</span> data_asia.loc[<span class="st">'Japan'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb35-2"><a href="#cb35-2" tabindex="-1"></a></span>
+<span id="cb35-3"><a href="#cb35-3" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb35-4"><a href="#cb35-4" tabindex="-1"></a>japan <span class="op">=</span> data_asia.loc[<span class="st">'Japan'</span>]</span></code></pre>
 </div>
 <ol style="list-style-type: decimal"><li>Complete the statements below to obtain the average GDP for Japan
 across the years reported for the 1980s.</li>
 </ol><div class="codewrapper sourceCode" id="cb36">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" aria-hidden="true" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
-<span id="cb36-2"><a href="#cb36-2" aria-hidden="true" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> ____)</span>
-<span id="cb36-3"><a href="#cb36-3" aria-hidden="true" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> ___] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> ___]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
+<span id="cb36-2"><a href="#cb36-2" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> ____)</span>
+<span id="cb36-3"><a href="#cb36-3" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> ___] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> ___]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
 </div>
 <ol start="2" style="list-style-type: decimal"><li>Abstract the code above into a single function.</li>
 </ol><div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
-<span id="cb37-2"><a href="#cb37-2" aria-hidden="true" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span><span class="op">+</span>___<span class="op">+</span><span class="st">'.csv'</span>,delimiter<span class="op">=</span><span class="st">','</span>,index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb37-3"><a href="#cb37-3" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb37-4"><a href="#cb37-4" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb37-5"><a href="#cb37-5" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb37-6"><a href="#cb37-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
+<span id="cb37-2"><a href="#cb37-2" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span><span class="op">+</span>___<span class="op">+</span><span class="st">'.csv'</span>,delimiter<span class="op">=</span><span class="st">','</span>,index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb37-3"><a href="#cb37-3" tabindex="-1"></a>    ____</span>
+<span id="cb37-4"><a href="#cb37-4" tabindex="-1"></a>    ____</span>
+<span id="cb37-5"><a href="#cb37-5" tabindex="-1"></a>    ____</span>
+<span id="cb37-6"><a href="#cb37-6" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
 </div>
 <ol start="3" style="list-style-type: decimal"><li>How would you generalize this function if you did not know
 beforehand which specific years occurred as columns in the data? For
@@ -1042,43 +1042,43 @@ <h4 class="accordion-header" id="headingSolution8">Show me the solution</h4>
 </ol><div class="codewrapper sourceCode" id="cb38">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
-<span id="cb38-2"><a href="#cb38-2" aria-hidden="true" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
-<span id="cb38-3"><a href="#cb38-3" aria-hidden="true" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
+<span id="cb38-2"><a href="#cb38-2" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
+<span id="cb38-3"><a href="#cb38-3" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
 </div>
 <ol start="2" style="list-style-type: decimal"><li>That code as a function is:</li>
 </ol><div class="codewrapper sourceCode" id="cb39">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
-<span id="cb39-2"><a href="#cb39-2" aria-hidden="true" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb39-3"><a href="#cb39-3" aria-hidden="true" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
-<span id="cb39-4"><a href="#cb39-4" aria-hidden="true" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
-<span id="cb39-5"><a href="#cb39-5" aria-hidden="true" tabindex="-1"></a>    avg <span class="op">=</span> (c.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> c.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>])<span class="op">/</span><span class="dv">2</span></span>
-<span id="cb39-6"><a href="#cb39-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
+<span id="cb39-2"><a href="#cb39-2" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb39-3"><a href="#cb39-3" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
+<span id="cb39-4"><a href="#cb39-4" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
+<span id="cb39-5"><a href="#cb39-5" tabindex="-1"></a>    avg <span class="op">=</span> (c.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> c.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>])<span class="op">/</span><span class="dv">2</span></span>
+<span id="cb39-6"><a href="#cb39-6" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
 </div>
 <ol start="3" style="list-style-type: decimal"><li>To obtain the average for the relevant years, we need to loop over
 them:</li>
 </ol><div class="codewrapper sourceCode" id="cb40">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
-<span id="cb40-2"><a href="#cb40-2" aria-hidden="true" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb40-3"><a href="#cb40-3" aria-hidden="true" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
-<span id="cb40-4"><a href="#cb40-4" aria-hidden="true" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
-<span id="cb40-5"><a href="#cb40-5" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> <span class="fl">0.0</span></span>
-<span id="cb40-6"><a href="#cb40-6" aria-hidden="true" tabindex="-1"></a>    num_years <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb40-7"><a href="#cb40-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> yr_header <span class="kw">in</span> c.index: <span class="co"># c's index contains reported years</span></span>
-<span id="cb40-8"><a href="#cb40-8" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> yr_header.startswith(gdp_decade):</span>
-<span id="cb40-9"><a href="#cb40-9" aria-hidden="true" tabindex="-1"></a>            total <span class="op">=</span> total <span class="op">+</span> c.loc[yr_header]</span>
-<span id="cb40-10"><a href="#cb40-10" aria-hidden="true" tabindex="-1"></a>            num_years <span class="op">=</span> num_years <span class="op">+</span> <span class="dv">1</span></span>
-<span id="cb40-11"><a href="#cb40-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> total<span class="op">/</span>num_years</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
+<span id="cb40-2"><a href="#cb40-2" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb40-3"><a href="#cb40-3" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
+<span id="cb40-4"><a href="#cb40-4" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
+<span id="cb40-5"><a href="#cb40-5" tabindex="-1"></a>    total <span class="op">=</span> <span class="fl">0.0</span></span>
+<span id="cb40-6"><a href="#cb40-6" tabindex="-1"></a>    num_years <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb40-7"><a href="#cb40-7" tabindex="-1"></a>    <span class="cf">for</span> yr_header <span class="kw">in</span> c.index: <span class="co"># c's index contains reported years</span></span>
+<span id="cb40-8"><a href="#cb40-8" tabindex="-1"></a>        <span class="cf">if</span> yr_header.startswith(gdp_decade):</span>
+<span id="cb40-9"><a href="#cb40-9" tabindex="-1"></a>            total <span class="op">=</span> total <span class="op">+</span> c.loc[yr_header]</span>
+<span id="cb40-10"><a href="#cb40-10" tabindex="-1"></a>            num_years <span class="op">=</span> num_years <span class="op">+</span> <span class="dv">1</span></span>
+<span id="cb40-11"><a href="#cb40-11" tabindex="-1"></a>    <span class="cf">return</span> total<span class="op">/</span>num_years</span></code></pre>
 </div>
 <p>The function can now be called by:</p>
 <div class="codewrapper sourceCode" id="cb41">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" aria-hidden="true" tabindex="-1"></a>avg_gdp_in_decade(<span class="st">'Japan'</span>,<span class="st">'asia'</span>,<span class="dv">1983</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" tabindex="-1"></a>avg_gdp_in_decade(<span class="st">'Japan'</span>,<span class="st">'asia'</span>,<span class="dv">1983</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1139,18 +1139,18 @@ <h4 class="accordion-header" id="headingSolution9">Show me the solution</h4>
 <ol style="list-style-type: decimal"><li><div class="codewrapper sourceCode" id="cb43">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a>  <span class="kw">def</span> logistic_map(x, r):</span>
-<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a>      <span class="cf">return</span> r <span class="op">*</span> x <span class="op">*</span> (<span class="dv">1</span> <span class="op">-</span> x)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" tabindex="-1"></a>  <span class="kw">def</span> logistic_map(x, r):</span>
+<span id="cb43-2"><a href="#cb43-2" tabindex="-1"></a>      <span class="cf">return</span> r <span class="op">*</span> x <span class="op">*</span> (<span class="dv">1</span> <span class="op">-</span> x)</span></code></pre>
 </div></li>
 <li><div class="codewrapper sourceCode" id="cb44">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" aria-hidden="true" tabindex="-1"></a>  initial_population <span class="op">=</span> <span class="fl">0.5</span></span>
-<span id="cb44-2"><a href="#cb44-2" aria-hidden="true" tabindex="-1"></a>  t_final <span class="op">=</span> <span class="dv">10</span></span>
-<span id="cb44-3"><a href="#cb44-3" aria-hidden="true" tabindex="-1"></a>  r <span class="op">=</span> <span class="fl">1.0</span></span>
-<span id="cb44-4"><a href="#cb44-4" aria-hidden="true" tabindex="-1"></a>  population <span class="op">=</span> [initial_population]</span>
-<span id="cb44-5"><a href="#cb44-5" aria-hidden="true" tabindex="-1"></a>  <span class="cf">for</span> t <span class="kw">in</span> <span class="bu">range</span>(t_final):</span>
-<span id="cb44-6"><a href="#cb44-6" aria-hidden="true" tabindex="-1"></a>      population.append( logistic_map(population[t], r) )</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" tabindex="-1"></a>  initial_population <span class="op">=</span> <span class="fl">0.5</span></span>
+<span id="cb44-2"><a href="#cb44-2" tabindex="-1"></a>  t_final <span class="op">=</span> <span class="dv">10</span></span>
+<span id="cb44-3"><a href="#cb44-3" tabindex="-1"></a>  r <span class="op">=</span> <span class="fl">1.0</span></span>
+<span id="cb44-4"><a href="#cb44-4" tabindex="-1"></a>  population <span class="op">=</span> [initial_population]</span>
+<span id="cb44-5"><a href="#cb44-5" tabindex="-1"></a>  <span class="cf">for</span> t <span class="kw">in</span> <span class="bu">range</span>(t_final):</span>
+<span id="cb44-6"><a href="#cb44-6" tabindex="-1"></a>      population.append( logistic_map(population[t], r) )</span></code></pre>
 </div></li>
 <li>```python def iterate(initial_population, t_final, r): population =
 [initial_population] for t in range(t_final): population.append(
@@ -1169,14 +1169,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </div>
 </div>
 </div>
-<div id="using-functions-with-conditionals-in-pandas" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="using-functions-with-conditionals-in-pandas" class="callout-inner">
-<h3 class="callout-title">Using Functions With Conditionals in
-Pandas<a class="anchor" aria-label="anchor" href="#using-functions-with-conditionals-in-pandas"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="using-functions-with-conditionals-in-pandas">Using Functions With Conditionals in
+Pandas<a class="anchor" aria-label="anchor" href="#using-functions-with-conditionals-in-pandas"></a></h3>
 <div class="callout-content">
 <p>Functions will often contain conditionals. Here is a short example
 that will indicate which quartile the argument is in based on hand-coded
@@ -1184,24 +1183,24 @@ <h3 class="callout-title">Using Functions With Conditionals in
 <div class="codewrapper sourceCode" id="cb46">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> calculate_life_quartile(exp):</span>
-<span id="cb46-2"><a href="#cb46-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> exp <span class="op">&lt;</span> <span class="fl">58.41</span>:</span>
-<span id="cb46-3"><a href="#cb46-3" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the first quartile</span></span>
-<span id="cb46-4"><a href="#cb46-4" aria-hidden="true" tabindex="-1"></a>        <span class="cf">return</span> <span class="dv">1</span></span>
-<span id="cb46-5"><a href="#cb46-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">58.41</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">67.05</span>:</span>
-<span id="cb46-6"><a href="#cb46-6" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the second quartile</span></span>
-<span id="cb46-7"><a href="#cb46-7" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">2</span></span>
-<span id="cb46-8"><a href="#cb46-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">67.05</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">71.70</span>:</span>
-<span id="cb46-9"><a href="#cb46-9" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the third quartile</span></span>
-<span id="cb46-10"><a href="#cb46-10" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">3</span></span>
-<span id="cb46-11"><a href="#cb46-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">71.70</span>:</span>
-<span id="cb46-12"><a href="#cb46-12" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the fourth quartile</span></span>
-<span id="cb46-13"><a href="#cb46-13" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">4</span></span>
-<span id="cb46-14"><a href="#cb46-14" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb46-15"><a href="#cb46-15" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation has bad data</span></span>
-<span id="cb46-16"><a href="#cb46-16" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="va">None</span></span>
-<span id="cb46-17"><a href="#cb46-17" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb46-18"><a href="#cb46-18" aria-hidden="true" tabindex="-1"></a>calculate_life_quartile(<span class="fl">62.5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" tabindex="-1"></a><span class="kw">def</span> calculate_life_quartile(exp):</span>
+<span id="cb46-2"><a href="#cb46-2" tabindex="-1"></a>    <span class="cf">if</span> exp <span class="op">&lt;</span> <span class="fl">58.41</span>:</span>
+<span id="cb46-3"><a href="#cb46-3" tabindex="-1"></a>        <span class="co"># This observation is in the first quartile</span></span>
+<span id="cb46-4"><a href="#cb46-4" tabindex="-1"></a>        <span class="cf">return</span> <span class="dv">1</span></span>
+<span id="cb46-5"><a href="#cb46-5" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">58.41</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">67.05</span>:</span>
+<span id="cb46-6"><a href="#cb46-6" tabindex="-1"></a>        <span class="co"># This observation is in the second quartile</span></span>
+<span id="cb46-7"><a href="#cb46-7" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">2</span></span>
+<span id="cb46-8"><a href="#cb46-8" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">67.05</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">71.70</span>:</span>
+<span id="cb46-9"><a href="#cb46-9" tabindex="-1"></a>        <span class="co"># This observation is in the third quartile</span></span>
+<span id="cb46-10"><a href="#cb46-10" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">3</span></span>
+<span id="cb46-11"><a href="#cb46-11" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">71.70</span>:</span>
+<span id="cb46-12"><a href="#cb46-12" tabindex="-1"></a>        <span class="co"># This observation is in the fourth quartile</span></span>
+<span id="cb46-13"><a href="#cb46-13" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">4</span></span>
+<span id="cb46-14"><a href="#cb46-14" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb46-15"><a href="#cb46-15" tabindex="-1"></a>        <span class="co"># This observation has bad data</span></span>
+<span id="cb46-16"><a href="#cb46-16" tabindex="-1"></a>       <span class="cf">return</span> <span class="va">None</span></span>
+<span id="cb46-17"><a href="#cb46-17" tabindex="-1"></a></span>
+<span id="cb46-18"><a href="#cb46-18" tabindex="-1"></a>calculate_life_quartile(<span class="fl">62.5</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1215,8 +1214,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb48">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>)</span>
-<span id="cb48-2"><a href="#cb48-2" aria-hidden="true" tabindex="-1"></a>data[<span class="st">'life_qrtl'</span>] <span class="op">=</span> data[<span class="st">'lifeExp_1952'</span>].<span class="bu">apply</span>(calculate_life_quartile)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>)</span>
+<span id="cb48-2"><a href="#cb48-2" tabindex="-1"></a>data[<span class="st">'life_qrtl'</span>] <span class="op">=</span> data[<span class="st">'lifeExp_1952'</span>].<span class="bu">apply</span>(calculate_life_quartile)</span></code></pre>
 </div>
 <p>There is a lot in that second line, so let’s take it piece by piece.
 On the right side of the <code>=</code> we start with
@@ -1307,7 +1306,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/16-writing-functions.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-07-24",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/17-scope.html b/instructor/17-scope.html
index 3bfdbaa74..f5fc0c58e 100644
--- a/instructor/17-scope.html
+++ b/instructor/17-scope.html
@@ -439,11 +439,11 @@ <h3 class="card-title">Objectives</h3>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">103.9</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> adjust(t):</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    temperature <span class="op">=</span> t <span class="op">*</span> <span class="fl">1.43</span> <span class="op">/</span> pressure</span>
-<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> temperature</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">103.9</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="kw">def</span> adjust(t):</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    temperature <span class="op">=</span> t <span class="op">*</span> <span class="fl">1.43</span> <span class="op">/</span> pressure</span>
+<span id="cb1-5"><a href="#cb1-5" tabindex="-1"></a>    <span class="cf">return</span> temperature</span></code></pre>
 </div>
 <ul><li>
 <code>pressure</code> is a <em>global variable</em>.
@@ -461,8 +461,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'adjusted:'</span>, adjust(<span class="fl">0.9</span>))</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'temperature after call:'</span>, temperature)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'adjusted:'</span>, adjust(<span class="fl">0.9</span>))</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'temperature after call:'</span>, temperature)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -490,13 +490,13 @@ <h3 class="callout-title">Local and Global Variable Use<a class="anchor" aria-la
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>limit <span class="op">=</span> <span class="dv">100</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> clip(value):</span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">min</span>(<span class="bu">max</span>(<span class="fl">0.0</span>, value), limit)</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a>value <span class="op">=</span> <span class="op">-</span><span class="fl">22.5</span></span>
-<span id="cb5-7"><a href="#cb5-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(clip(value))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>limit <span class="op">=</span> <span class="dv">100</span></span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a></span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a><span class="kw">def</span> clip(value):</span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">min</span>(<span class="bu">max</span>(<span class="fl">0.0</span>, value), limit)</span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a></span>
+<span id="cb5-6"><a href="#cb5-6" tabindex="-1"></a>value <span class="op">=</span> <span class="op">-</span><span class="fl">22.5</span></span>
+<span id="cb5-7"><a href="#cb5-7" tabindex="-1"></a><span class="bu">print</span>(clip(value))</span></code></pre>
 </div>
 </div>
 </div>
@@ -547,7 +547,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <ol style="list-style-type: decimal"><li>Three levels.</li>
 <li><code>errors_02.py</code></li>
@@ -636,7 +636,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/17-scope.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/18-style.html b/instructor/18-style.html
index 32b879f19..f9162d7e2 100644
--- a/instructor/18-style.html
+++ b/instructor/18-style.html
@@ -474,10 +474,10 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> calc_bulk_density(mass, volume):</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">'''Return dry bulk density = powder mass / powder volume.'''</span></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">assert</span> volume <span class="op">&gt;</span> <span class="dv">0</span></span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> mass <span class="op">/</span> volume</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="kw">def</span> calc_bulk_density(mass, volume):</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>    <span class="co">'''Return dry bulk density = powder mass / powder volume.'''</span></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    <span class="cf">assert</span> volume <span class="op">&gt;</span> <span class="dv">0</span></span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    <span class="cf">return</span> mass <span class="op">/</span> volume</span></code></pre>
 </div>
 <p>If the assertion is <code>False</code>, the Python interpreter raises
 an <code>AssertionError</code> runtime exception. The source code for
@@ -495,14 +495,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">"Return average of values, or None if no values are supplied."</span></span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
-<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span>
-<span id="cb2-7"><a href="#cb2-7" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb2-8"><a href="#cb2-8" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(average)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a>    <span class="co">"Return average of values, or None if no values are supplied."</span></span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a></span>
+<span id="cb2-4"><a href="#cb2-4" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb2-5"><a href="#cb2-5" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
+<span id="cb2-6"><a href="#cb2-6" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span>
+<span id="cb2-7"><a href="#cb2-7" tabindex="-1"></a></span>
+<span id="cb2-8"><a href="#cb2-8" tabindex="-1"></a><span class="bu">help</span>(average)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -512,13 +512,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 average(values)
     Return average of values, or None if no values are supplied.</code></pre>
 </div>
-<div id="multiline-strings" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="multiline-strings" class="callout-inner">
-<h3 class="callout-title">Multiline Strings<a class="anchor" aria-label="anchor" href="#multiline-strings"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="multiline-strings">Multiline Strings<a class="anchor" aria-label="anchor" href="#multiline-strings"></a></h3>
 <div class="callout-content">
 <p>Often use <em>multiline strings</em> for documentation. These start
 and end with three quote characters (either single or double) and end
@@ -526,10 +525,10 @@ <h3 class="callout-title">Multiline Strings<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="co">"""This string spans</span></span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="co">multiple lines.</span></span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a><span class="co">Blank lines are allowed."""</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="co">"""This string spans</span></span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a><span class="co">multiple lines.</span></span>
+<span id="cb4-3"><a href="#cb4-3" tabindex="-1"></a></span>
+<span id="cb4-4"><a href="#cb4-4" tabindex="-1"></a><span class="co">Blank lines are allowed."""</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -548,22 +547,22 @@ <h3 class="callout-title">What Will Be Shown?<a class="anchor" aria-label="ancho
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="co">"Find maximum edit distance between multiple sequences."</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="co"># This finds the maximum distance between all sequences.</span></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> overall_max(sequences):</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>    <span class="co">'''Determine overall maximum edit distance.'''</span></span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-7"><a href="#cb5-7" aria-hidden="true" tabindex="-1"></a>    highest <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb5-8"><a href="#cb5-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> left <span class="kw">in</span> sequences:</span>
-<span id="cb5-9"><a href="#cb5-9" aria-hidden="true" tabindex="-1"></a>        <span class="cf">for</span> right <span class="kw">in</span> sequences:</span>
-<span id="cb5-10"><a href="#cb5-10" aria-hidden="true" tabindex="-1"></a>            <span class="co">'''Avoid checking sequence against itself.'''</span></span>
-<span id="cb5-11"><a href="#cb5-11" aria-hidden="true" tabindex="-1"></a>            <span class="cf">if</span> left <span class="op">!=</span> right:</span>
-<span id="cb5-12"><a href="#cb5-12" aria-hidden="true" tabindex="-1"></a>                this <span class="op">=</span> edit_distance(left, right)</span>
-<span id="cb5-13"><a href="#cb5-13" aria-hidden="true" tabindex="-1"></a>                highest <span class="op">=</span> <span class="bu">max</span>(highest, this)</span>
-<span id="cb5-14"><a href="#cb5-14" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-15"><a href="#cb5-15" aria-hidden="true" tabindex="-1"></a>    <span class="co"># Report.</span></span>
-<span id="cb5-16"><a href="#cb5-16" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> highest</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="co">"Find maximum edit distance between multiple sequences."</span></span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="co"># This finds the maximum distance between all sequences.</span></span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a></span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a><span class="kw">def</span> overall_max(sequences):</span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a>    <span class="co">'''Determine overall maximum edit distance.'''</span></span>
+<span id="cb5-6"><a href="#cb5-6" tabindex="-1"></a></span>
+<span id="cb5-7"><a href="#cb5-7" tabindex="-1"></a>    highest <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb5-8"><a href="#cb5-8" tabindex="-1"></a>    <span class="cf">for</span> left <span class="kw">in</span> sequences:</span>
+<span id="cb5-9"><a href="#cb5-9" tabindex="-1"></a>        <span class="cf">for</span> right <span class="kw">in</span> sequences:</span>
+<span id="cb5-10"><a href="#cb5-10" tabindex="-1"></a>            <span class="co">'''Avoid checking sequence against itself.'''</span></span>
+<span id="cb5-11"><a href="#cb5-11" tabindex="-1"></a>            <span class="cf">if</span> left <span class="op">!=</span> right:</span>
+<span id="cb5-12"><a href="#cb5-12" tabindex="-1"></a>                this <span class="op">=</span> edit_distance(left, right)</span>
+<span id="cb5-13"><a href="#cb5-13" tabindex="-1"></a>                highest <span class="op">=</span> <span class="bu">max</span>(highest, this)</span>
+<span id="cb5-14"><a href="#cb5-14" tabindex="-1"></a></span>
+<span id="cb5-15"><a href="#cb5-15" tabindex="-1"></a>    <span class="co"># Report.</span></span>
+<span id="cb5-16"><a href="#cb5-16" tabindex="-1"></a>    <span class="cf">return</span> highest</span></code></pre>
 </div>
 </div>
 </div>
@@ -589,12 +588,12 @@ <h3 class="callout-title">Document This<a class="anchor" aria-label="anchor" hre
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># Return the middle value of three.</span></span>
-<span id="cb6-3"><a href="#cb6-3" aria-hidden="true" tabindex="-1"></a>    <span class="co"># Assumes the values can actually be compared.</span></span>
-<span id="cb6-4"><a href="#cb6-4" aria-hidden="true" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
-<span id="cb6-5"><a href="#cb6-5" aria-hidden="true" tabindex="-1"></a>    values.sort()</span>
-<span id="cb6-6"><a href="#cb6-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
+<span id="cb6-2"><a href="#cb6-2" tabindex="-1"></a>    <span class="co"># Return the middle value of three.</span></span>
+<span id="cb6-3"><a href="#cb6-3" tabindex="-1"></a>    <span class="co"># Assumes the values can actually be compared.</span></span>
+<span id="cb6-4"><a href="#cb6-4" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
+<span id="cb6-5"><a href="#cb6-5" tabindex="-1"></a>    values.sort()</span>
+<span id="cb6-6"><a href="#cb6-6" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -604,17 +603,17 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">'''Return the middle value of three.</span></span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a><span class="co">    Assumes the values can actually be compared.'''</span></span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
-<span id="cb7-5"><a href="#cb7-5" aria-hidden="true" tabindex="-1"></a>    values.sort()</span>
-<span id="cb7-6"><a href="#cb7-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>    <span class="co">'''Return the middle value of three.</span></span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a><span class="co">    Assumes the values can actually be compared.'''</span></span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
+<span id="cb7-5"><a href="#cb7-5" tabindex="-1"></a>    values.sort()</span>
+<span id="cb7-6"><a href="#cb7-6" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -637,21 +636,21 @@ <h3 class="callout-title">Clean Up This Code<a class="anchor" aria-label="anchor
 </ol><div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a>n <span class="op">=</span> <span class="dv">10</span></span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>s <span class="op">=</span> <span class="st">'et cetera'</span></span>
-<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(s)</span>
-<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb8-5"><a href="#cb8-5" aria-hidden="true" tabindex="-1"></a><span class="cf">while</span> i <span class="op">&lt;</span> n:</span>
-<span id="cb8-6"><a href="#cb8-6" aria-hidden="true" tabindex="-1"></a>    <span class="co"># print('at', j)</span></span>
-<span id="cb8-7"><a href="#cb8-7" aria-hidden="true" tabindex="-1"></a>    new <span class="op">=</span> <span class="st">''</span></span>
-<span id="cb8-8"><a href="#cb8-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(<span class="bu">len</span>(s)):</span>
-<span id="cb8-9"><a href="#cb8-9" aria-hidden="true" tabindex="-1"></a>        left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
-<span id="cb8-10"><a href="#cb8-10" aria-hidden="true" tabindex="-1"></a>        right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>)<span class="op">%</span><span class="bu">len</span>(s)</span>
-<span id="cb8-11"><a href="#cb8-11" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> s[left]<span class="op">==</span>s[right]: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
-<span id="cb8-12"><a href="#cb8-12" aria-hidden="true" tabindex="-1"></a>        <span class="cf">else</span>: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
-<span id="cb8-13"><a href="#cb8-13" aria-hidden="true" tabindex="-1"></a>    s<span class="op">=</span><span class="st">''</span>.join(new)</span>
-<span id="cb8-14"><a href="#cb8-14" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(s)</span>
-<span id="cb8-15"><a href="#cb8-15" aria-hidden="true" tabindex="-1"></a>    i <span class="op">+=</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a>n <span class="op">=</span> <span class="dv">10</span></span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a>s <span class="op">=</span> <span class="st">'et cetera'</span></span>
+<span id="cb8-3"><a href="#cb8-3" tabindex="-1"></a><span class="bu">print</span>(s)</span>
+<span id="cb8-4"><a href="#cb8-4" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb8-5"><a href="#cb8-5" tabindex="-1"></a><span class="cf">while</span> i <span class="op">&lt;</span> n:</span>
+<span id="cb8-6"><a href="#cb8-6" tabindex="-1"></a>    <span class="co"># print('at', j)</span></span>
+<span id="cb8-7"><a href="#cb8-7" tabindex="-1"></a>    new <span class="op">=</span> <span class="st">''</span></span>
+<span id="cb8-8"><a href="#cb8-8" tabindex="-1"></a>    <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(<span class="bu">len</span>(s)):</span>
+<span id="cb8-9"><a href="#cb8-9" tabindex="-1"></a>        left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
+<span id="cb8-10"><a href="#cb8-10" tabindex="-1"></a>        right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>)<span class="op">%</span><span class="bu">len</span>(s)</span>
+<span id="cb8-11"><a href="#cb8-11" tabindex="-1"></a>        <span class="cf">if</span> s[left]<span class="op">==</span>s[right]: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
+<span id="cb8-12"><a href="#cb8-12" tabindex="-1"></a>        <span class="cf">else</span>: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
+<span id="cb8-13"><a href="#cb8-13" tabindex="-1"></a>    s<span class="op">=</span><span class="st">''</span>.join(new)</span>
+<span id="cb8-14"><a href="#cb8-14" tabindex="-1"></a>    <span class="bu">print</span>(s)</span>
+<span id="cb8-15"><a href="#cb8-15" tabindex="-1"></a>    i <span class="op">+=</span> <span class="dv">1</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -661,37 +660,37 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>Here’s one solution.</p>
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> string_machine(input_string, iterations):</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">"""</span></span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a><span class="co">    Takes input_string and generates a new string with -'s and *'s</span></span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="co">    corresponding to characters that have identical adjacent characters</span></span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a><span class="co">    or not, respectively.  Iterates through this procedure with the resultant</span></span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a><span class="co">    strings for the supplied number of iterations.</span></span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="co">    """</span></span>
-<span id="cb9-8"><a href="#cb9-8" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(input_string)</span>
-<span id="cb9-9"><a href="#cb9-9" aria-hidden="true" tabindex="-1"></a>    input_string_length <span class="op">=</span> <span class="bu">len</span>(input_string)</span>
-<span id="cb9-10"><a href="#cb9-10" aria-hidden="true" tabindex="-1"></a>    old <span class="op">=</span> input_string</span>
-<span id="cb9-11"><a href="#cb9-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(iterations):</span>
-<span id="cb9-12"><a href="#cb9-12" aria-hidden="true" tabindex="-1"></a>        new <span class="op">=</span> <span class="st">''</span></span>
-<span id="cb9-13"><a href="#cb9-13" aria-hidden="true" tabindex="-1"></a>        <span class="co"># iterate through characters in previous string</span></span>
-<span id="cb9-14"><a href="#cb9-14" aria-hidden="true" tabindex="-1"></a>        <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(input_string_length):</span>
-<span id="cb9-15"><a href="#cb9-15" aria-hidden="true" tabindex="-1"></a>            left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
-<span id="cb9-16"><a href="#cb9-16" aria-hidden="true" tabindex="-1"></a>            right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>) <span class="op">%</span> input_string_length  <span class="co"># ensure right index wraps around</span></span>
-<span id="cb9-17"><a href="#cb9-17" aria-hidden="true" tabindex="-1"></a>            <span class="cf">if</span> old[left] <span class="op">==</span> old[right]:</span>
-<span id="cb9-18"><a href="#cb9-18" aria-hidden="true" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
-<span id="cb9-19"><a href="#cb9-19" aria-hidden="true" tabindex="-1"></a>            <span class="cf">else</span>:</span>
-<span id="cb9-20"><a href="#cb9-20" aria-hidden="true" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
-<span id="cb9-21"><a href="#cb9-21" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(new)</span>
-<span id="cb9-22"><a href="#cb9-22" aria-hidden="true" tabindex="-1"></a>        <span class="co"># store new string as old</span></span>
-<span id="cb9-23"><a href="#cb9-23" aria-hidden="true" tabindex="-1"></a>        old <span class="op">=</span> new     </span>
-<span id="cb9-24"><a href="#cb9-24" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb9-25"><a href="#cb9-25" aria-hidden="true" tabindex="-1"></a>string_machine(<span class="st">'et cetera'</span>, <span class="dv">10</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="kw">def</span> string_machine(input_string, iterations):</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>    <span class="co">"""</span></span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a><span class="co">    Takes input_string and generates a new string with -'s and *'s</span></span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a><span class="co">    corresponding to characters that have identical adjacent characters</span></span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a><span class="co">    or not, respectively.  Iterates through this procedure with the resultant</span></span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a><span class="co">    strings for the supplied number of iterations.</span></span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a><span class="co">    """</span></span>
+<span id="cb9-8"><a href="#cb9-8" tabindex="-1"></a>    <span class="bu">print</span>(input_string)</span>
+<span id="cb9-9"><a href="#cb9-9" tabindex="-1"></a>    input_string_length <span class="op">=</span> <span class="bu">len</span>(input_string)</span>
+<span id="cb9-10"><a href="#cb9-10" tabindex="-1"></a>    old <span class="op">=</span> input_string</span>
+<span id="cb9-11"><a href="#cb9-11" tabindex="-1"></a>    <span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(iterations):</span>
+<span id="cb9-12"><a href="#cb9-12" tabindex="-1"></a>        new <span class="op">=</span> <span class="st">''</span></span>
+<span id="cb9-13"><a href="#cb9-13" tabindex="-1"></a>        <span class="co"># iterate through characters in previous string</span></span>
+<span id="cb9-14"><a href="#cb9-14" tabindex="-1"></a>        <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(input_string_length):</span>
+<span id="cb9-15"><a href="#cb9-15" tabindex="-1"></a>            left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
+<span id="cb9-16"><a href="#cb9-16" tabindex="-1"></a>            right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>) <span class="op">%</span> input_string_length  <span class="co"># ensure right index wraps around</span></span>
+<span id="cb9-17"><a href="#cb9-17" tabindex="-1"></a>            <span class="cf">if</span> old[left] <span class="op">==</span> old[right]:</span>
+<span id="cb9-18"><a href="#cb9-18" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
+<span id="cb9-19"><a href="#cb9-19" tabindex="-1"></a>            <span class="cf">else</span>:</span>
+<span id="cb9-20"><a href="#cb9-20" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
+<span id="cb9-21"><a href="#cb9-21" tabindex="-1"></a>        <span class="bu">print</span>(new)</span>
+<span id="cb9-22"><a href="#cb9-22" tabindex="-1"></a>        <span class="co"># store new string as old</span></span>
+<span id="cb9-23"><a href="#cb9-23" tabindex="-1"></a>        old <span class="op">=</span> new     </span>
+<span id="cb9-24"><a href="#cb9-24" tabindex="-1"></a></span>
+<span id="cb9-25"><a href="#cb9-25" tabindex="-1"></a>string_machine(<span class="st">'et cetera'</span>, <span class="dv">10</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -784,7 +783,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/18-style.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-07-29",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/19-wrap.html b/instructor/19-wrap.html
index aad4deca7..b2c922f16 100644
--- a/instructor/19-wrap.html
+++ b/instructor/19-wrap.html
@@ -518,7 +518,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/19-wrap.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/20-feedback.html b/instructor/20-feedback.html
index 708841619..4be1cb7a6 100644
--- a/instructor/20-feedback.html
+++ b/instructor/20-feedback.html
@@ -488,7 +488,7 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/20-feedback.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/404.html b/instructor/404.html
index 5d9da35a7..29e122011 100644
--- a/instructor/404.html
+++ b/instructor/404.html
@@ -464,8 +464,8 @@ <h1>Page not found</h1>
   "url": "https://swcarpentry.github.io/python-novice-gapminder/instructor/404.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/404.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/CODE_OF_CONDUCT.html b/instructor/CODE_OF_CONDUCT.html
index 84405a737..15bfe9ea0 100644
--- a/instructor/CODE_OF_CONDUCT.html
+++ b/instructor/CODE_OF_CONDUCT.html
@@ -456,7 +456,7 @@ <h1>Contributor Code of Conduct</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/CODE_OF_CONDUCT.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/LICENSE.html b/instructor/LICENSE.html
index 36c9c6185..2bb92414a 100644
--- a/instructor/LICENSE.html
+++ b/instructor/LICENSE.html
@@ -507,7 +507,7 @@ <h1>Licenses</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/LICENSE.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/aio.html b/instructor/aio.html
index 7ccbf2091..6fb7eaf27 100644
--- a/instructor/aio.html
+++ b/instructor/aio.html
@@ -564,12 +564,12 @@ <h3 class="card-title">Objectives</h3>
 <li>Type code into the browser and see the results after your JupyterLab
 server has finished executing your code</li>
 </ul>
-<div id="jupyterlab-what-about-jupyter-notebooks" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="jupyterlab-what-about-jupyter-notebooks" class="callout-inner">
-<h3 class="callout-title">JupyterLab? What about Jupyter notebooks?<a class="anchor" aria-label="anchor" href="#jupyterlab-what-about-jupyter-notebooks"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="jupyterlab-what-about-jupyter-notebooks">JupyterLab? What about Jupyter notebooks?<a class="anchor" aria-label="anchor" href="#jupyterlab-what-about-jupyter-notebooks"></a>
 </h3>
 <div class="callout-content">
 <p>JupyterLab is the <a href="https://jupyterlab.readthedocs.io/en/stable/getting_started/overview.html#overview" class="external-link">next
@@ -608,7 +608,7 @@ <h3 id="macos---command-line">macOS - Command Line<a class="anchor" aria-label="
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">BASH<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
+<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
 </div>
 </div>
 <div class="section level3">
@@ -622,7 +622,7 @@ <h3 id="windows-users---command-line">Windows Users - Command Line<a class="anch
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">BASH<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
+<pre class="sourceCode bash" tabindex="0"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="ex">$</span> jupyter lab</span></code></pre>
 </div>
 </div>
 <div class="section level3">
@@ -696,12 +696,12 @@ <h3 id="menu-bar">Menu Bar<a class="anchor" aria-label="anchor" href="#menu-bar"
 <strong>Help:</strong> A list of JupyterLab and kernel help
 links.</li>
 </ul>
-<div id="kernels" class="callout callout">
+<div id="callout2" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="kernels" class="callout-inner">
-<h3 class="callout-title">Kernels<a class="anchor" aria-label="anchor" href="#kernels"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="kernels">Kernels<a class="anchor" aria-label="anchor" href="#kernels"></a>
 </h3>
 <div class="callout-content">
 <p>The JupyterLab <a href="https://jupyterlab.readthedocs.io/en/stable/user/documents_kernels.html" class="external-link">docs</a>
@@ -791,12 +791,12 @@ <h3 id="main-work-area">Main Work Area<a class="anchor" aria-label="anchor" href
 notebook documentation</a>.</p>
 <p align="center">
 <img alt="Example Jupyter Notebook" src="../fig/0_jupyterlab_notebook_screenshot.png" width="750" class="figure"></p>
-<div id="how-its-stored" class="callout callout">
+<div id="callout3" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="how-its-stored" class="callout-inner">
-<h3 class="callout-title">How It’s Stored<a class="anchor" aria-label="anchor" href="#how-its-stored"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="how-its-stored">How It’s Stored<a class="anchor" aria-label="anchor" href="#how-its-stored"></a>
 </h3>
 <div class="callout-content">
 <ul>
@@ -846,12 +846,12 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </div>
 </div>
 </div>
-<div id="code-vs.-text" class="callout callout">
+<div id="callout4" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="code-vs.-text" class="callout-inner">
-<h3 class="callout-title">Code vs. Text<a class="anchor" aria-label="anchor" href="#code-vs.-text"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="code-vs--text">Code vs. Text<a class="anchor" aria-label="anchor" href="#code-vs--text"></a>
 </h3>
 <div class="callout-content">
 <p>Jupyter mixes code and text in different types of blocks, called
@@ -1125,8 +1125,8 @@ <h3 class="callout-title">More Math<a class="anchor" aria-label="anchor" href="#
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="dv">7</span> <span class="op">*</span> <span class="dv">3</span></span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="dv">2</span> <span class="op">+</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="dv">7</span> <span class="op">*</span> <span class="dv">3</span></span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="dv">2</span> <span class="op">+</span> <span class="dv">1</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -1142,7 +1142,7 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="dv">3</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="dv">3</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -1163,8 +1163,8 @@ <h3 class="callout-title">Change an Existing Cell from Code to
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span></span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(x)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span></span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a><span class="bu">print</span>(x)</span></code></pre>
 </div>
 <p>And then run it with <kbd>Shift</kbd>+<kbd>Return</kbd> to be sure
 that it works as a code cell. Now go back to the cell and use
@@ -1188,7 +1188,7 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span> <span class="bu">print</span>(x)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>x <span class="op">=</span> <span class="dv">6</span> <span class="op">*</span> <span class="dv">7</span> <span class="op">+</span> <span class="dv">12</span> <span class="bu">print</span>(x)</span></code></pre>
 </div>
 </div>
 </div>
@@ -1346,8 +1346,8 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">42</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>first_name <span class="op">=</span> <span class="st">'Ahmed'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">42</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>first_name <span class="op">=</span> <span class="st">'Ahmed'</span></span></code></pre>
 </div>
 </li>
 </ul></section><section id="use-print-to-display-values."><h2 class="section-heading">Use <code>print</code> to display values.<a class="anchor" aria-label="anchor" href="#use-print-to-display-values."></a>
@@ -1369,7 +1369,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(first_name, <span class="st">'is'</span>, age, <span class="st">'years old'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(first_name, <span class="st">'is'</span>, age, <span class="st">'years old'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1392,7 +1392,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(last_name)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="bu">print</span>(last_name)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1409,12 +1409,12 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 informative.</li>
 <li>We will look at error messages in detail <a href="17-scope.html#reading-error-messages">later</a>.</li>
 </ul>
-<div id="variables-persist-between-cells" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="variables-persist-between-cells" class="callout-inner">
-<h3 class="callout-title">Variables Persist Between Cells<a class="anchor" aria-label="anchor" href="#variables-persist-between-cells"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="variables-persist-between-cells">Variables Persist Between Cells<a class="anchor" aria-label="anchor" href="#variables-persist-between-cells"></a>
 </h3>
 <div class="callout-content">
 <p>Be aware that it is the <em>order</em> of execution of cells that is
@@ -1428,12 +1428,12 @@ <h3 class="callout-title">Variables Persist Between Cells<a class="anchor" aria-
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(myval)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a><span class="bu">print</span>(myval)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>myval <span class="op">=</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>myval <span class="op">=</span> <span class="dv">1</span></span></code></pre>
 </div>
 <p>If you execute this in order, the first cell will give an error.
 However, if you run the first cell <em>after</em> the second cell it
@@ -1458,8 +1458,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> age <span class="op">+</span> <span class="dv">3</span></span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Age in three years:'</span>, age)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a>age <span class="op">=</span> age <span class="op">+</span> <span class="dv">3</span></span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Age in three years:'</span>, age)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1481,13 +1481,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <li>Use the position’s index in square brackets to get the character at
 that position.</li>
 </ul>
-<figure><img src="../fig/2_indexing.svg" alt="" class="figure mx-auto d-block"><figcaption>A line of Python code, print(atom_name[0]),
+<figure><img src="../fig/2_indexing.svg" alt="A line of Python code, print(atom_name[0]), demonstrates that using the zero index will output just the initial letter, in this case ‘h’ for helium." class="figure mx-auto d-block"><div class="figcaption">A line of Python code, print(atom_name[0]),
 demonstrates that using the zero index will output just the initial
-letter, in this case ‘h’ for helium.</figcaption></figure><div class="codewrapper sourceCode" id="cb10">
+letter, in this case ‘h’ for helium.</div>
+</figure><div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'helium'</span></span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'helium'</span></span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1518,8 +1519,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'sodium'</span></span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>:<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'sodium'</span></span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a><span class="bu">print</span>(atom_name[<span class="dv">0</span>:<span class="dv">3</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1533,7 +1534,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="st">'helium'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="st">'helium'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1561,9 +1562,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>flabadab <span class="op">=</span> <span class="dv">42</span></span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a>ewr_422_yY <span class="op">=</span> <span class="st">'Ahmed'</span></span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(ewr_422_yY, <span class="st">'is'</span>, flabadab, <span class="st">'years old'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>flabadab <span class="op">=</span> <span class="dv">42</span></span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a>ewr_422_yY <span class="op">=</span> <span class="st">'Ahmed'</span></span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a><span class="bu">print</span>(ewr_422_yY, <span class="st">'is'</span>, flabadab, <span class="st">'years old'</span>)</span></code></pre>
 </div>
 <ul>
 <li>Use meaningful variable names to help other people understand what
@@ -1583,12 +1584,12 @@ <h3 class="callout-title">Swapping Values<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Command  # Value of x   # Value of y   # Value of swap #</span></span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> <span class="fl">1.0</span>    <span class="co">#              #              #               #</span></span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a>y <span class="op">=</span> <span class="fl">3.0</span>    <span class="co">#              #              #               #</span></span>
-<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a>swap <span class="op">=</span> x   <span class="co">#              #              #               #</span></span>
-<span id="cb17-5"><a href="#cb17-5" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> y      <span class="co">#              #              #               #</span></span>
-<span id="cb17-6"><a href="#cb17-6" aria-hidden="true" tabindex="-1"></a>y <span class="op">=</span> swap   <span class="co">#              #              #               #</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="co"># Command  # Value of x   # Value of y   # Value of swap #</span></span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>x <span class="op">=</span> <span class="fl">1.0</span>    <span class="co">#              #              #               #</span></span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a>y <span class="op">=</span> <span class="fl">3.0</span>    <span class="co">#              #              #               #</span></span>
+<span id="cb17-4"><a href="#cb17-4" tabindex="-1"></a>swap <span class="op">=</span> x   <span class="co">#              #              #               #</span></span>
+<span id="cb17-5"><a href="#cb17-5" tabindex="-1"></a>x <span class="op">=</span> y      <span class="co">#              #              #               #</span></span>
+<span id="cb17-6"><a href="#cb17-6" tabindex="-1"></a>y <span class="op">=</span> swap   <span class="co">#              #              #               #</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -1598,7 +1599,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1631,9 +1632,9 @@ <h3 class="callout-title">Predicting Values<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'left'</span></span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>position <span class="op">=</span> initial</span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'right'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'left'</span></span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>position <span class="op">=</span> initial</span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a>initial <span class="op">=</span> <span class="st">'right'</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -1643,12 +1644,12 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(position)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a><span class="bu">print</span>(position)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1683,7 +1684,7 @@ <h3 class="callout-title">Challenge<a class="anchor" aria-label="anchor" href="#
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Numbers are not strings or sequences and Python will raise an error
 if you try to perform an index operation on a number. In the <a href="03-types-conversion.html">next lesson on types and type
@@ -1694,8 +1695,8 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">=</span> <span class="dv">123</span></span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>a <span class="op">=</span> <span class="dv">123</span></span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1705,8 +1706,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">=</span> <span class="bu">str</span>(<span class="dv">123</span>)</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a>a <span class="op">=</span> <span class="bu">str</span>(<span class="dv">123</span>)</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a><span class="bu">print</span>(a[<span class="dv">1</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1741,7 +1742,7 @@ <h3 class="callout-title">Choosing a Name<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p><code>minutes</code> is better because <code>min</code> might mean
 something like “minimum” (and actually is an existing built-in function
@@ -1762,8 +1763,8 @@ <h3 class="callout-title">Slicing practice<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'carbon'</span></span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'atom_name[1:3] is:'</span>, atom_name[<span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>atom_name <span class="op">=</span> <span class="st">'carbon'</span></span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'atom_name[1:3] is:'</span>, atom_name[<span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -1773,7 +1774,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1796,7 +1797,7 @@ <h3 class="callout-title">Slicing concepts<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>species_name <span class="op">=</span> <span class="st">"Acacia buxifolia"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>species_name <span class="op">=</span> <span class="st">"Acacia buxifolia"</span></span></code></pre>
 </div>
 <p>What would these expressions return?</p>
 <ol style="list-style-type: decimal">
@@ -1823,7 +1824,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Solutions</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <ol style="list-style-type: decimal">
 <li>
@@ -1954,7 +1955,7 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="dv">52</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="dv">52</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1964,8 +1965,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>fitness <span class="op">=</span> <span class="st">'average'</span></span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(fitness))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a>fitness <span class="op">=</span> <span class="st">'average'</span></span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(fitness))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1982,7 +1983,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span> <span class="op">-</span> <span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span> <span class="op">-</span> <span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -1992,7 +1993,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'hello'</span> <span class="op">-</span> <span class="st">'h'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'hello'</span> <span class="op">-</span> <span class="st">'h'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2013,8 +2014,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>full_name <span class="op">=</span> <span class="st">'Ahmed'</span> <span class="op">+</span> <span class="st">' '</span> <span class="op">+</span> <span class="st">'Walsh'</span></span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(full_name)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>full_name <span class="op">=</span> <span class="st">'Ahmed'</span> <span class="op">+</span> <span class="st">' '</span> <span class="op">+</span> <span class="st">'Walsh'</span></span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="bu">print</span>(full_name)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2033,8 +2034,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>separator <span class="op">=</span> <span class="st">'='</span> <span class="op">*</span> <span class="dv">10</span></span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(separator)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>separator <span class="op">=</span> <span class="st">'='</span> <span class="op">*</span> <span class="dv">10</span></span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="bu">print</span>(separator)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2051,7 +2052,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(full_name))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(full_name))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2064,7 +2065,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="dv">52</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(<span class="dv">52</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2086,7 +2087,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2107,8 +2108,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="bu">int</span>(<span class="st">'2'</span>))</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">str</span>(<span class="dv">1</span>) <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">1</span> <span class="op">+</span> <span class="bu">int</span>(<span class="st">'2'</span>))</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">str</span>(<span class="dv">1</span>) <span class="op">+</span> <span class="st">'2'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2129,8 +2130,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'half is'</span>, <span class="dv">1</span> <span class="op">/</span> <span class="fl">2.0</span>)</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'three squared is'</span>, <span class="fl">3.0</span> <span class="op">**</span> <span class="dv">2</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'half is'</span>, <span class="dv">1</span> <span class="op">/</span> <span class="fl">2.0</span>)</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'three squared is'</span>, <span class="fl">3.0</span> <span class="op">**</span> <span class="dv">2</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2149,10 +2150,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">1</span></span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a>variable_two <span class="op">=</span> <span class="dv">5</span> <span class="op">*</span> variable_one</span>
-<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">2</span></span>
-<span id="cb23-4"><a href="#cb23-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first is'</span>, variable_one, <span class="st">'and second is'</span>, variable_two)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">1</span></span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a>variable_two <span class="op">=</span> <span class="dv">5</span> <span class="op">*</span> variable_one</span>
+<span id="cb23-3"><a href="#cb23-3" tabindex="-1"></a>variable_one <span class="op">=</span> <span class="dv">2</span></span>
+<span id="cb23-4"><a href="#cb23-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first is'</span>, variable_one, <span class="st">'and second is'</span>, variable_two)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2185,7 +2186,7 @@ <h3 class="callout-title">Fractions<a class="anchor" aria-label="anchor" href="#
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>It is a floating-point number (often abbreviated “float”). It is
 possible to find out by using the built-in function
@@ -2193,7 +2194,7 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="fl">3.4</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">type</span>(<span class="fl">3.4</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2221,15 +2222,15 @@ <h3 class="callout-title">Automatic Type Conversion<a class="anchor" aria-label=
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>It is a float: integers are automatically converted to floats as
 necessary.</p>
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="fl">3.25</span> <span class="op">+</span> <span class="dv">4</span></span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result, <span class="st">'is'</span>, <span class="bu">type</span>(result))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>result <span class="op">=</span> <span class="fl">3.25</span> <span class="op">+</span> <span class="dv">4</span></span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a><span class="bu">print</span>(result, <span class="st">'is'</span>, <span class="bu">type</span>(result))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2269,7 +2270,7 @@ <h3 class="callout-title">Choose a Type<a class="anchor" aria-label="anchor" hre
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>The answers to the questions are:</p>
 <ol style="list-style-type: decimal">
@@ -2304,9 +2305,9 @@ <h3 class="callout-title">Division Types<a class="anchor" aria-label="anchor" hr
 <div class="codewrapper sourceCode" id="cb29">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 // 3:'</span>, <span class="dv">5</span> <span class="op">//</span> <span class="dv">3</span>)</span>
-<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 / 3:'</span>, <span class="dv">5</span> <span class="op">/</span> <span class="dv">3</span>)</span>
-<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 % 3:'</span>, <span class="dv">5</span> <span class="op">%</span> <span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 // 3:'</span>, <span class="dv">5</span> <span class="op">//</span> <span class="dv">3</span>)</span>
+<span id="cb29-2"><a href="#cb29-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 / 3:'</span>, <span class="dv">5</span> <span class="op">/</span> <span class="dv">3</span>)</span>
+<span id="cb29-3"><a href="#cb29-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'5 % 3:'</span>, <span class="dv">5</span> <span class="op">%</span> <span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2327,7 +2328,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>We want the minimum number of surveys that reaches everyone once,
 which is the rounded up value of
@@ -2339,11 +2340,11 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>num_subjects <span class="op">=</span> <span class="dv">600</span></span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a>num_per_survey <span class="op">=</span> <span class="dv">42</span></span>
-<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a>num_surveys <span class="op">=</span> (num_subjects <span class="op">-</span> <span class="dv">1</span>) <span class="op">//</span> num_per_survey <span class="op">+</span> <span class="dv">1</span></span>
-<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb31-5"><a href="#cb31-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(num_subjects, <span class="st">'subjects,'</span>, num_per_survey, <span class="st">'per survey:'</span>, num_surveys)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>num_subjects <span class="op">=</span> <span class="dv">600</span></span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a>num_per_survey <span class="op">=</span> <span class="dv">42</span></span>
+<span id="cb31-3"><a href="#cb31-3" tabindex="-1"></a>num_surveys <span class="op">=</span> (num_subjects <span class="op">-</span> <span class="dv">1</span>) <span class="op">//</span> num_per_survey <span class="op">+</span> <span class="dv">1</span></span>
+<span id="cb31-4"><a href="#cb31-4" tabindex="-1"></a></span>
+<span id="cb31-5"><a href="#cb31-5" tabindex="-1"></a><span class="bu">print</span>(num_subjects, <span class="st">'subjects,'</span>, num_per_survey, <span class="st">'per survey:'</span>, num_surveys)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2368,8 +2369,8 @@ <h3 class="callout-title">Strings to Numbers<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb33">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"3.4"</span>))</span>
-<span id="cb33-2"><a href="#cb33-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"float to int:"</span>, <span class="bu">int</span>(<span class="fl">3.4</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"3.4"</span>))</span>
+<span id="cb33-2"><a href="#cb33-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"float to int:"</span>, <span class="bu">int</span>(<span class="fl">3.4</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2382,7 +2383,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"Hello world!"</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"string to float:"</span>, <span class="bu">float</span>(<span class="st">"Hello world!"</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2401,7 +2402,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"fractional string to int:"</span>, <span class="bu">int</span>(<span class="st">"3.4"</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"fractional string to int:"</span>, <span class="bu">int</span>(<span class="st">"3.4"</span>))</span></code></pre>
 </div>
 </div>
 </div>
@@ -2411,7 +2412,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>What do you expect this program to do? It would not be so
 unreasonable to expect the Python 3 <code>int</code> command to convert
@@ -2421,7 +2422,7 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb38">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a><span class="bu">int</span>(<span class="st">"3.4"</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" tabindex="-1"></a><span class="bu">int</span>(<span class="st">"3.4"</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2438,7 +2439,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb40">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a><span class="bu">int</span>(<span class="bu">float</span>(<span class="st">"3.4"</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" tabindex="-1"></a><span class="bu">int</span>(<span class="bu">float</span>(<span class="st">"3.4"</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2462,9 +2463,9 @@ <h3 class="callout-title">Arithmetic with Different Types<a class="anchor" aria-
 <div class="codewrapper sourceCode" id="cb42">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" aria-hidden="true" tabindex="-1"></a>first <span class="op">=</span> <span class="fl">1.0</span></span>
-<span id="cb42-2"><a href="#cb42-2" aria-hidden="true" tabindex="-1"></a>second <span class="op">=</span> <span class="st">"1"</span></span>
-<span id="cb42-3"><a href="#cb42-3" aria-hidden="true" tabindex="-1"></a>third <span class="op">=</span> <span class="st">"1.1"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" tabindex="-1"></a>first <span class="op">=</span> <span class="fl">1.0</span></span>
+<span id="cb42-2"><a href="#cb42-2" tabindex="-1"></a>second <span class="op">=</span> <span class="st">"1"</span></span>
+<span id="cb42-3"><a href="#cb42-3" tabindex="-1"></a>third <span class="op">=</span> <span class="st">"1.1"</span></span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li><code>first + float(second)</code></li>
@@ -2482,7 +2483,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Show me the solution</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <p>Answer: 1 and 4</p>
 </div>
@@ -2504,9 +2505,9 @@ <h3 class="callout-title">Complex Numbers<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb43">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a>a_complex_number <span class="op">=</span> <span class="dv">6</span> <span class="op">+</span> <span class="ot">2j</span></span>
-<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.real)</span>
-<span id="cb43-3"><a href="#cb43-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.imag)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" tabindex="-1"></a>a_complex_number <span class="op">=</span> <span class="dv">6</span> <span class="op">+</span> <span class="ot">2j</span></span>
+<span id="cb43-2"><a href="#cb43-2" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.real)</span>
+<span id="cb43-3"><a href="#cb43-3" tabindex="-1"></a><span class="bu">print</span>(a_complex_number.imag)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2529,7 +2530,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
 <div class="accordion-body">
 <ol style="list-style-type: decimal">
 <li>Standard mathematics treatments typically use <code>i</code> to
@@ -2619,8 +2620,8 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="co"># This sentence isn't executed by Python.</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>adjustment <span class="op">=</span> <span class="fl">0.5</span>   <span class="co"># Neither is this - anything after '#' is ignored.</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="co"># This sentence isn't executed by Python.</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>adjustment <span class="op">=</span> <span class="fl">0.5</span>   <span class="co"># Neither is this - anything after '#' is ignored.</span></span></code></pre>
 </div>
 </section><section id="a-function-may-take-zero-or-more-arguments."><h2 class="section-heading">A function may take zero or more arguments.<a class="anchor" aria-label="anchor" href="#a-function-may-take-zero-or-more-arguments."></a>
 </h2>
@@ -2647,9 +2648,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'before'</span>)</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>()</span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'after'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'before'</span>)</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a><span class="bu">print</span>()</span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'after'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2670,8 +2671,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">print</span>(<span class="st">'example'</span>)</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of print is'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">print</span>(<span class="st">'example'</span>)</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of print is'</span>, result)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2696,8 +2697,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>))</span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">min</span>(<span class="st">'a'</span>, <span class="st">'A'</span>, <span class="st">'0'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>))</span>
+<span id="cb6-2"><a href="#cb6-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">min</span>(<span class="st">'a'</span>, <span class="st">'A'</span>, <span class="st">'0'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2723,7 +2724,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="st">'a'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="dv">1</span>, <span class="st">'a'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2745,7 +2746,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2758,7 +2759,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>, <span class="dv">1</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="bu">round</span>(<span class="fl">3.712</span>, <span class="dv">1</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2779,13 +2780,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>  <span class="co"># creation of a string object </span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(my_string))       <span class="co"># the len function takes a string as an argument and returns the length of the string</span></span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.swapcase()) <span class="co"># calling the swapcase method on the my_string object</span></span>
-<span id="cb14-6"><a href="#cb14-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb14-7"><a href="#cb14-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.<span class="fu">__len__</span>())  <span class="co"># calling the internal __len__ method on the my_string object, used by len(my_string)</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>  <span class="co"># creation of a string object </span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a></span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">len</span>(my_string))       <span class="co"># the len function takes a string as an argument and returns the length of the string</span></span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a></span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a><span class="bu">print</span>(my_string.swapcase()) <span class="co"># calling the swapcase method on the my_string object</span></span>
+<span id="cb14-6"><a href="#cb14-6" tabindex="-1"></a></span>
+<span id="cb14-7"><a href="#cb14-7" tabindex="-1"></a><span class="bu">print</span>(my_string.<span class="fu">__len__</span>())  <span class="co"># calling the internal __len__ method on the my_string object, used by len(my_string)</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2801,10 +2802,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.isupper())          <span class="co"># Not all the letters are uppercase</span></span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.upper())            <span class="co"># This capitalizes all the letters</span></span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(my_string.upper().isupper())  <span class="co"># Now all the letters are uppercase</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a><span class="bu">print</span>(my_string.isupper())          <span class="co"># Not all the letters are uppercase</span></span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a><span class="bu">print</span>(my_string.upper())            <span class="co"># This capitalizes all the letters</span></span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a></span>
+<span id="cb16-4"><a href="#cb16-4" tabindex="-1"></a><span class="bu">print</span>(my_string.upper().isupper())  <span class="co"># Now all the letters are uppercase</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2823,7 +2824,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(<span class="bu">round</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a><span class="bu">help</span>(<span class="bu">round</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2859,8 +2860,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Forgot to close the quote marks around the string.</span></span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>name <span class="op">=</span> <span class="st">'Feng</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a><span class="co"># Forgot to close the quote marks around the string.</span></span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>name <span class="op">=</span> <span class="st">'Feng</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2873,8 +2874,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a><span class="co"># An extra '=' in the assignment.</span></span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> <span class="op">=</span> <span class="dv">52</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a><span class="co"># An extra '=' in the assignment.</span></span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>age <span class="op">=</span> <span class="op">=</span> <span class="dv">52</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2890,7 +2891,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"hello world"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"hello world"</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2920,8 +2921,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">53</span></span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a>remaining <span class="op">=</span> <span class="dv">100</span> <span class="op">-</span> aege <span class="co"># mis-spelled 'age'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>age <span class="op">=</span> <span class="dv">53</span></span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a>remaining <span class="op">=</span> <span class="dv">100</span> <span class="op">-</span> aege <span class="co"># mis-spelled 'age'</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -2954,8 +2955,8 @@ <h3 class="callout-title">What Happens When<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>radiance <span class="op">=</span> <span class="fl">1.0</span></span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a>radiance <span class="op">=</span> <span class="bu">max</span>(<span class="fl">2.1</span>, <span class="fl">2.0</span> <span class="op">+</span> <span class="bu">min</span>(radiance, <span class="fl">1.1</span> <span class="op">*</span> radiance <span class="op">-</span> <span class="fl">0.5</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>radiance <span class="op">=</span> <span class="fl">1.0</span></span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a>radiance <span class="op">=</span> <span class="bu">max</span>(<span class="fl">2.1</span>, <span class="fl">2.0</span> <span class="op">+</span> <span class="bu">min</span>(radiance, <span class="fl">1.1</span> <span class="op">*</span> radiance <span class="op">-</span> <span class="fl">0.5</span>))</span></code></pre>
 </div>
 </div>
 </div>
@@ -2998,12 +2999,12 @@ <h3 class="callout-title">Spot the Difference<a class="anchor" aria-label="ancho
 <div class="codewrapper sourceCode" id="cb29">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a>easy_string <span class="op">=</span> <span class="st">"abc"</span></span>
-<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span>
-<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a>rich <span class="op">=</span> <span class="st">"gold"</span></span>
-<span id="cb29-4"><a href="#cb29-4" aria-hidden="true" tabindex="-1"></a>poor <span class="op">=</span> <span class="st">"tin"</span></span>
-<span id="cb29-5"><a href="#cb29-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span>
-<span id="cb29-6"><a href="#cb29-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" tabindex="-1"></a>easy_string <span class="op">=</span> <span class="st">"abc"</span></span>
+<span id="cb29-2"><a href="#cb29-2" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span>
+<span id="cb29-3"><a href="#cb29-3" tabindex="-1"></a>rich <span class="op">=</span> <span class="st">"gold"</span></span>
+<span id="cb29-4"><a href="#cb29-4" tabindex="-1"></a>poor <span class="op">=</span> <span class="st">"tin"</span></span>
+<span id="cb29-5"><a href="#cb29-5" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span>
+<span id="cb29-6"><a href="#cb29-6" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
 </div>
 </div>
 </div>
@@ -3018,7 +3019,7 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(easy_string))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3028,7 +3029,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(rich, poor))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3038,7 +3039,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a><span class="bu">print</span>(<span class="bu">max</span>(<span class="bu">len</span>(rich), <span class="bu">len</span>(poor)))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3117,12 +3118,12 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </div>
 </div>
 </div>
-<div id="explore-the-python-docs" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="explore-the-python-docs" class="callout-inner">
-<h3 class="callout-title">Explore the Python docs!<a class="anchor" aria-label="anchor" href="#explore-the-python-docs"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="explore-the-python-docs">Explore the Python docs!<a class="anchor" aria-label="anchor" href="#explore-the-python-docs"></a>
 </h3>
 <div class="callout-content">
 <p>The <a href="https://docs.python.org/3/" class="external-link">official Python
@@ -3246,12 +3247,12 @@ <h3 class="card-title">Objectives</h3>
 Index).</li>
 <li>We will see later how to write new libraries.</li>
 </ul>
-<div id="libraries-and-modules" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="libraries-and-modules" class="callout-inner">
-<h3 class="callout-title">Libraries and modules<a class="anchor" aria-label="anchor" href="#libraries-and-modules"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="libraries-and-modules">Libraries and modules<a class="anchor" aria-label="anchor" href="#libraries-and-modules"></a>
 </h3>
 <div class="callout-content">
 <p>A library is a collection of modules, but the terms are often used
@@ -3278,10 +3279,10 @@ <h3 class="callout-title">Libraries and modules<a class="anchor" aria-label="anc
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pi is'</span>, math.pi)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, math.cos(math.pi))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> math</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pi is'</span>, math.pi)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, math.cos(math.pi))</span></code></pre>
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 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3308,7 +3309,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(math)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="bu">help</span>(math)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3348,9 +3349,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> cos, pi</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, cos(pi))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> cos, pi</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a></span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, cos(pi))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3369,9 +3370,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, m.cos(m.pi))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a></span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'cos(pi) is'</span>, m.cos(m.pi))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3442,7 +3443,7 @@ <h3 class="callout-title">Locating the Right Module<a class="anchor" aria-label=
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">'ACTTGCTTGAC'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">'ACTTGCTTGAC'</span></span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>Which <a href="https://docs.python.org/3/library/" class="external-link">standard
@@ -3471,18 +3472,18 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>random_index <span class="op">=</span> randrange(<span class="bu">len</span>(bases))</span>
-<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(bases[random_index])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a></span>
+<span id="cb10-3"><a href="#cb10-3" tabindex="-1"></a>random_index <span class="op">=</span> randrange(<span class="bu">len</span>(bases))</span>
+<span id="cb10-4"><a href="#cb10-4" tabindex="-1"></a><span class="bu">print</span>(bases[random_index])</span></code></pre>
 </div>
 <p>or more compactly:</p>
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(bases[randrange(<span class="bu">len</span>(bases))])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> randrange</span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a></span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a><span class="bu">print</span>(bases[randrange(<span class="bu">len</span>(bases))])</span></code></pre>
 </div>
 <p>Perhaps you found the <a href="https://docs.python.org/3/library/random.html#random.sample" class="external-link"><code>random.sample</code></a>
 function? It allows for slightly less typing but might be a bit harder
@@ -3490,9 +3491,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> sample</span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(sample(bases, <span class="dv">1</span>)[<span class="dv">0</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> sample</span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a></span>
+<span id="cb12-3"><a href="#cb12-3" tabindex="-1"></a><span class="bu">print</span>(sample(bases, <span class="dv">1</span>)[<span class="dv">0</span>])</span></code></pre>
 </div>
 <p>Note that this function returns a list of values. We will learn about
 lists in <a href="11-lists.html">episode 11</a>.</p>
@@ -3501,9 +3502,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> choice</span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(choice(bases))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a><span class="im">from</span> random <span class="im">import</span> choice</span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a></span>
+<span id="cb13-3"><a href="#cb13-3" tabindex="-1"></a><span class="bu">print</span>(choice(bases))</span></code></pre>
 </div>
 </div>
 </div>
@@ -3524,12 +3525,12 @@ <h3 class="callout-title">Jigsaw Puzzle (Parson’s Problem) Programming
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>bases<span class="op">=</span><span class="st">"ACTTGCTTGAC"</span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math</span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a>___ <span class="op">=</span> random.randrange(n_bases)</span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a>___ <span class="op">=</span> <span class="bu">len</span>(bases)</span>
-<span id="cb14-6"><a href="#cb14-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base "</span>, bases[___], <span class="st">"base index"</span>, ___)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>bases<span class="op">=</span><span class="st">"ACTTGCTTGAC"</span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a><span class="im">import</span> math</span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a>___ <span class="op">=</span> random.randrange(n_bases)</span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a>___ <span class="op">=</span> <span class="bu">len</span>(bases)</span>
+<span id="cb14-6"><a href="#cb14-6" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base "</span>, bases[___], <span class="st">"base index"</span>, ___)</span></code></pre>
 </div>
 </div>
 </div>
@@ -3544,12 +3545,12 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math </span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">"ACTTGCTTGAC"</span> </span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a>n_bases <span class="op">=</span> <span class="bu">len</span>(bases)</span>
-<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a>idx <span class="op">=</span> random.randrange(n_bases)</span>
-<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base"</span>, bases[idx], <span class="st">"base index"</span>, idx)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="im">import</span> math </span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a>bases <span class="op">=</span> <span class="st">"ACTTGCTTGAC"</span> </span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a>n_bases <span class="op">=</span> <span class="bu">len</span>(bases)</span>
+<span id="cb15-5"><a href="#cb15-5" tabindex="-1"></a>idx <span class="op">=</span> random.randrange(n_bases)</span>
+<span id="cb15-6"><a href="#cb15-6" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"random base"</span>, bases[idx], <span class="st">"base index"</span>, idx)</span></code></pre>
 </div>
 </div>
 </div>
@@ -3604,9 +3605,9 @@ <h3 class="callout-title">Importing With Aliases<a class="anchor" aria-label="an
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> ____.degrees(____.pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(____)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>angle <span class="op">=</span> ____.degrees(____.pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a><span class="bu">print</span>(____)</span></code></pre>
 </div>
 </div>
 </div>
@@ -3621,17 +3622,17 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
-<span id="cb18-2"><a href="#cb18-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> m.degrees(m.pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb18-3"><a href="#cb18-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a><span class="im">import</span> math <span class="im">as</span> m</span>
+<span id="cb18-2"><a href="#cb18-2" tabindex="-1"></a>angle <span class="op">=</span> m.degrees(m.pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb18-3"><a href="#cb18-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 <p>can be written as</p>
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> math</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> math.degrees(math.pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="im">import</span> math</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>angle <span class="op">=</span> math.degrees(math.pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 <p>Since you just wrote the code and are familiar with it, you might
 actually find the first version easier to read. But when trying to read
@@ -3722,9 +3723,9 @@ <h3 class="callout-title">Importing Specific Items<a class="anchor" aria-label="
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>____ math <span class="im">import</span> ____, ____</span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>____ math <span class="im">import</span> ____, ____</span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 </div>
 </div>
@@ -3739,9 +3740,9 @@ <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> degrees, pi</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> degrees, pi</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a>angle <span class="op">=</span> degrees(pi <span class="op">/</span> <span class="dv">2</span>)</span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="bu">print</span>(angle)</span></code></pre>
 </div>
 <p>Most likely you find this version easier to read since it’s less
 dense. The main reason not to use this form of import is to avoid name
@@ -3770,8 +3771,8 @@ <h3 class="callout-title">Reading Error Messages<a class="anchor" aria-label="an
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> log</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>log(<span class="dv">0</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a><span class="im">from</span> math <span class="im">import</span> log</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>log(<span class="dv">0</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -3889,10 +3890,10 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>data_oceania <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>data_oceania <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a><span class="bu">print</span>(data_oceania)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3922,12 +3923,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 multiple dataframes so we won’t accidentally overwrite a dataframe or
 read from the wrong one.</li>
 </ul>
-<div id="file-not-found" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="file-not-found" class="callout-inner">
-<h3 class="callout-title">File Not Found<a class="anchor" aria-label="anchor" href="#file-not-found"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="file-not-found">File Not Found<a class="anchor" aria-label="anchor" href="#file-not-found"></a>
 </h3>
 <div class="callout-content">
 <p>Our lessons store their data files in a <code>data</code>
@@ -3960,8 +3961,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>data_oceania_country <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a>data_oceania_country <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -3988,7 +3989,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>data_oceania_country.info()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a>data_oceania_country.info()</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4042,7 +4043,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.columns)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.columns)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4064,7 +4065,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.T)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.T)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4093,7 +4094,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.describe())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="bu">print</span>(data_oceania_country.describe())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4152,7 +4153,7 @@ <h3 class="callout-title">Reading Other Data<a class="anchor" aria-label="anchor
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <p>To read in a CSV, we use <code>pd.read_csv</code> and pass the
 filename <code>'data/gapminder_gdp_americas.csv'</code> to it. We also
@@ -4163,8 +4164,8 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>data_americas <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_americas.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a>data_americas.describe()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>data_americas <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_americas.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a>data_americas.describe()</span></code></pre>
 </div>
 </div>
 </div>
@@ -4196,7 +4197,7 @@ <h3 class="callout-title">Inspecting Data<a class="anchor" aria-label="anchor" h
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <ol style="list-style-type: decimal">
 <li>We can check out the first five rows of <code>data_americas</code>
@@ -4209,7 +4210,7 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>data_americas.head(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a>data_americas.head(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4249,14 +4250,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>americas_flipped <span class="op">=</span> data_americas.T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>americas_flipped <span class="op">=</span> data_americas.T</span></code></pre>
 </div>
 <p>We can then view the last three columns of <code>americas</code> by
 viewing the last three rows of <code>americas_flipped</code>:</p>
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4286,14 +4287,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>).T    </span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>americas_flipped.tail(n<span class="op">=</span><span class="dv">3</span>).T    </span></code></pre>
 </div>
 <p><strong>Note:</strong> we could have done the above in a single line
 of code by ‘chaining’ the commands:</p>
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a>data_americas.T.tail(n<span class="op">=</span><span class="dv">3</span>).T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a>data_americas.T.tail(n<span class="op">=</span><span class="dv">3</span>).T</span></code></pre>
 </div>
 </div>
 </div>
@@ -4331,7 +4332,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <p>We need to specify the path to the file of interest in the call to
 <code>pd.read_csv</code>. We first need to ‘jump’ out of the folder
@@ -4341,7 +4342,7 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a>data_microbes <span class="op">=</span> pd.read_csv(<span class="st">'../field_data/microbes.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a>data_microbes <span class="op">=</span> pd.read_csv(<span class="st">'../field_data/microbes.csv'</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -4369,22 +4370,22 @@ <h3 class="callout-title">Writing Data<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <p>In order to write the DataFrame <code>data_americas</code> to a file
 called <code>processed.csv</code>, execute the following command:</p>
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a>data_americas.to_csv(<span class="st">'processed.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a>data_americas.to_csv(<span class="st">'processed.csv'</span>)</span></code></pre>
 </div>
 <p>For help on <code>read_csv</code> or <code>to_csv</code>, you could
 execute, for example:</p>
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(data_americas.to_csv)</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(pd.read_csv)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="bu">help</span>(data_americas.to_csv)</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a><span class="bu">help</span>(pd.read_csv)</span></code></pre>
 </div>
 <p>Note that <code>help(to_csv)</code> or <code>help(pd.to_csv)</code>
 throws an error! This is due to the fact that <code>to_csv</code> is not
@@ -4491,9 +4492,9 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.iloc[<span class="dv">0</span>, <span class="dv">0</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="bu">print</span>(data.iloc[<span class="dv">0</span>, <span class="dv">0</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4510,7 +4511,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4526,7 +4527,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, :])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">"Albania"</span>, :])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4552,7 +4553,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[:, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[:, <span class="st">"gdpPercap_1952"</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4581,7 +4582,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4610,7 +4611,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">max</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">max</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4623,7 +4624,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">min</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a><span class="bu">print</span>(data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>].<span class="bu">min</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4644,12 +4645,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Use a subset of data to keep output readable.</span></span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>subset <span class="op">=</span> data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>]</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Subset of data:</span><span class="ch">\n</span><span class="st">'</span>, subset)</span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Which values were greater than 10000 ?</span></span>
-<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'</span><span class="ch">\n</span><span class="st">Where are values large?</span><span class="ch">\n</span><span class="st">'</span>, subset <span class="op">&gt;</span> <span class="dv">10000</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="co"># Use a subset of data to keep output readable.</span></span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>subset <span class="op">=</span> data.loc[<span class="st">'Italy'</span>:<span class="st">'Poland'</span>, <span class="st">'gdpPercap_1962'</span>:<span class="st">'gdpPercap_1972'</span>]</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'Subset of data:</span><span class="ch">\n</span><span class="st">'</span>, subset)</span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a></span>
+<span id="cb15-5"><a href="#cb15-5" tabindex="-1"></a><span class="co"># Which values were greater than 10000 ?</span></span>
+<span id="cb15-6"><a href="#cb15-6" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'</span><span class="ch">\n</span><span class="st">Where are values large?</span><span class="ch">\n</span><span class="st">'</span>, subset <span class="op">&gt;</span> <span class="dv">10000</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4682,8 +4683,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>mask <span class="op">=</span> subset <span class="op">&gt;</span> <span class="dv">10000</span></span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(subset[mask])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>mask <span class="op">=</span> subset <span class="op">&gt;</span> <span class="dv">10000</span></span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a><span class="bu">print</span>(subset[mask])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4705,7 +4706,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(subset[subset <span class="op">&gt;</span> <span class="dv">10000</span>].describe())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="bu">print</span>(subset[subset <span class="op">&gt;</span> <span class="dv">10000</span>].describe())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4729,7 +4730,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
   <h3 class="accordion-header" id="headingInstructor1">
 <div class="note-square"><i aria-hidden="true" class="callout-icon" data-feather="edit-2"></i></div>Instructor Note</h3>
 </button>
-<div id="collapseInstructor1" class="accordion-collapse collapse" data-bs-parent="#accordionInstructor1" aria-labelledby="headingInstructor1">
+<div id="collapseInstructor1" class="accordion-collapse collapse" aria-labelledby="headingInstructor1" data-bs-parent="#accordionInstructor1">
 <div class="accordion-body">
 <p>Learners often struggle here, many may not work with financial data
 and concepts so they find the example concepts difficult to get their
@@ -4758,9 +4759,9 @@ <h3 class="accordion-header" id="headingInstructor1">
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a>mask_higher <span class="op">=</span> data <span class="op">&gt;</span> data.mean()</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a>wealth_score <span class="op">=</span> mask_higher.aggregate(<span class="st">'sum'</span>, axis<span class="op">=</span><span class="dv">1</span>) <span class="op">/</span> <span class="bu">len</span>(data.columns)</span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(wealth_score)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a>mask_higher <span class="op">=</span> data <span class="op">&gt;</span> data.mean()</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a>wealth_score <span class="op">=</span> mask_higher.aggregate(<span class="st">'sum'</span>, axis<span class="op">=</span><span class="dv">1</span>) <span class="op">/</span> <span class="bu">len</span>(data.columns)</span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="bu">print</span>(wealth_score)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4804,7 +4805,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.groupby(wealth_score).<span class="bu">sum</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="bu">print</span>(data.groupby(wealth_score).<span class="bu">sum</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -4840,9 +4841,9 @@ <h3 class="callout-title">Selection of Individual Values<a class="anchor" aria-l
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a></span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
 </div>
 <p>Write an expression to find the Per Capita GDP of Serbia in 2007.</p>
 </div>
@@ -4853,14 +4854,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>The selection can be done by using the labels for both the row
 (“Serbia”) and the column (“gdpPercap_2007”):</p>
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Serbia'</span>, <span class="st">'gdpPercap_2007'</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Serbia'</span>, <span class="st">'gdpPercap_2007'</span>])</span></code></pre>
 </div>
 <p>The output is</p>
 <div class="codewrapper">
@@ -4888,8 +4889,8 @@ <h3 class="callout-title">Extent of Slicing<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_europe.iloc[<span class="dv">0</span>:<span class="dv">2</span>, <span class="dv">0</span>:<span class="dv">2</span>])</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Albania'</span>:<span class="st">'Belgium'</span>, <span class="st">'gdpPercap_1952'</span>:<span class="st">'gdpPercap_1962'</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a><span class="bu">print</span>(data_europe.iloc[<span class="dv">0</span>:<span class="dv">2</span>, <span class="dv">0</span>:<span class="dv">2</span>])</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a><span class="bu">print</span>(data_europe.loc[<span class="st">'Albania'</span>:<span class="st">'Belgium'</span>, <span class="st">'gdpPercap_1952'</span>:<span class="st">'gdpPercap_1962'</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -4899,7 +4900,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>No, they do not produce the same output! The output of the first
 statement is:</p>
@@ -4944,11 +4945,11 @@ <h3 class="callout-title">Reconstructing Data<a class="anchor" aria-label="ancho
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span>
-<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span>
-<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span>
-<span id="cb31-5"><a href="#cb31-5" aria-hidden="true" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span>
+<span id="cb31-3"><a href="#cb31-3" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span>
+<span id="cb31-4"><a href="#cb31-4" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span>
+<span id="cb31-5"><a href="#cb31-5" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -4958,13 +4959,13 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>Let’s go through this piece of code line by line.</p>
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" tabindex="-1"></a>first <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span></code></pre>
 </div>
 <p>This line loads the dataset containing the GDP data from all
 countries into a dataframe called <code>first</code>. The
@@ -4973,7 +4974,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb33">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" tabindex="-1"></a>second <span class="op">=</span> first[first[<span class="st">'continent'</span>] <span class="op">==</span> <span class="st">'Americas'</span>]</span></code></pre>
 </div>
 <p>This line makes a selection: only those rows of <code>first</code>
 for which the ‘continent’ column matches ‘Americas’ are extracted.
@@ -4985,7 +4986,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a>third <span class="op">=</span> second.drop(<span class="st">'Puerto Rico'</span>)</span></code></pre>
 </div>
 <p>As the syntax suggests, this line drops the row from
 <code>second</code> where the label is ‘Puerto Rico’. The resulting
@@ -4994,7 +4995,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a>fourth <span class="op">=</span> third.drop(<span class="st">'continent'</span>, axis <span class="op">=</span> <span class="dv">1</span>)</span></code></pre>
 </div>
 <p>Again we apply the drop function, but in this case we are dropping
 not a row but a whole column. To accomplish this, we need to specify
@@ -5003,7 +5004,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb36">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" aria-hidden="true" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" tabindex="-1"></a>fourth.to_csv(<span class="st">'result.csv'</span>)</span></code></pre>
 </div>
 <p>The final step is to write the data that we have been working on to a
 csv file. Pandas makes this easy with the <code>to_csv()</code>
@@ -5028,9 +5029,9 @@ <h3 class="callout-title">Selecting Indices<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb37-2"><a href="#cb37-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.idxmin())</span>
-<span id="cb37-3"><a href="#cb37-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data.idxmax())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb37-2"><a href="#cb37-2" tabindex="-1"></a><span class="bu">print</span>(data.idxmin())</span>
+<span id="cb37-3"><a href="#cb37-3" tabindex="-1"></a><span class="bu">print</span>(data.idxmax())</span></code></pre>
 </div>
 </div>
 </div>
@@ -5040,7 +5041,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <p>For each column in <code>data</code>, <code>idxmin</code> will return
 the index value corresponding to each column’s minimum;
@@ -5078,25 +5079,25 @@ <h3 class="callout-title">Practice with Selection<a class="anchor" aria-label="a
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <p>1:</p>
 <div class="codewrapper sourceCode" id="cb38">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a>data[<span class="st">'gdpPercap_1982'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" tabindex="-1"></a>data[<span class="st">'gdpPercap_1982'</span>]</span></code></pre>
 </div>
 <p>2:</p>
 <div class="codewrapper sourceCode" id="cb39">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">'Denmark'</span>,:]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" tabindex="-1"></a>data.loc[<span class="st">'Denmark'</span>,:]</span></code></pre>
 </div>
 <p>3:</p>
 <div class="codewrapper sourceCode" id="cb40">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a>data.loc[:,<span class="st">'gdpPercap_1985'</span>:]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" tabindex="-1"></a>data.loc[:,<span class="st">'gdpPercap_1985'</span>:]</span></code></pre>
 </div>
 <p>Pandas is smart enough to recognize the number at the end of the
 column label and does not give you an error, although no column named
@@ -5106,7 +5107,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb41">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" aria-hidden="true" tabindex="-1"></a>data[<span class="st">'gdpPercap_2007'</span>]<span class="op">/</span>data[<span class="st">'gdpPercap_1952'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" tabindex="-1"></a>data[<span class="st">'gdpPercap_2007'</span>]<span class="op">/</span>data[<span class="st">'gdpPercap_1952'</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -5143,141 +5144,141 @@ <h3 class="callout-title">Many Ways of Access<a class="anchor" aria-label="ancho
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Show me the solution</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <p>1. Access a single column:</p>
 <div class="codewrapper sourceCode" id="cb42">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb42-2"><a href="#cb42-2" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"col_name"</span>]   <span class="co"># as a Series</span></span>
-<span id="cb42-3"><a href="#cb42-3" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]] <span class="co"># as a DataFrame</span></span>
-<span id="cb42-4"><a href="#cb42-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-5"><a href="#cb42-5" aria-hidden="true" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
-<span id="cb42-6"><a href="#cb42-6" aria-hidden="true" tabindex="-1"></a>data.T.loc[<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb42-7"><a href="#cb42-7" aria-hidden="true" tabindex="-1"></a>data.T.loc[[<span class="st">"col_name"</span>]].T  <span class="co"># as a DataFrame</span></span>
-<span id="cb42-8"><a href="#cb42-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-9"><a href="#cb42-9" aria-hidden="true" tabindex="-1"></a><span class="co"># Dot notation (Series)</span></span>
-<span id="cb42-10"><a href="#cb42-10" aria-hidden="true" tabindex="-1"></a>data.col_name</span>
-<span id="cb42-11"><a href="#cb42-11" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-12"><a href="#cb42-12" aria-hidden="true" tabindex="-1"></a><span class="co"># by index (iloc)</span></span>
-<span id="cb42-13"><a href="#cb42-13" aria-hidden="true" tabindex="-1"></a>data.iloc[:, col_index]   <span class="co"># as a Series</span></span>
-<span id="cb42-14"><a href="#cb42-14" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col_index]] <span class="co"># as a DataFrame</span></span>
-<span id="cb42-15"><a href="#cb42-15" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb42-16"><a href="#cb42-16" aria-hidden="true" tabindex="-1"></a><span class="co"># using a mask</span></span>
-<span id="cb42-17"><a href="#cb42-17" aria-hidden="true" tabindex="-1"></a>data.T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb42-2"><a href="#cb42-2" tabindex="-1"></a>data[<span class="st">"col_name"</span>]   <span class="co"># as a Series</span></span>
+<span id="cb42-3"><a href="#cb42-3" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]] <span class="co"># as a DataFrame</span></span>
+<span id="cb42-4"><a href="#cb42-4" tabindex="-1"></a></span>
+<span id="cb42-5"><a href="#cb42-5" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
+<span id="cb42-6"><a href="#cb42-6" tabindex="-1"></a>data.T.loc[<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb42-7"><a href="#cb42-7" tabindex="-1"></a>data.T.loc[[<span class="st">"col_name"</span>]].T  <span class="co"># as a DataFrame</span></span>
+<span id="cb42-8"><a href="#cb42-8" tabindex="-1"></a></span>
+<span id="cb42-9"><a href="#cb42-9" tabindex="-1"></a><span class="co"># Dot notation (Series)</span></span>
+<span id="cb42-10"><a href="#cb42-10" tabindex="-1"></a>data.col_name</span>
+<span id="cb42-11"><a href="#cb42-11" tabindex="-1"></a></span>
+<span id="cb42-12"><a href="#cb42-12" tabindex="-1"></a><span class="co"># by index (iloc)</span></span>
+<span id="cb42-13"><a href="#cb42-13" tabindex="-1"></a>data.iloc[:, col_index]   <span class="co"># as a Series</span></span>
+<span id="cb42-14"><a href="#cb42-14" tabindex="-1"></a>data.iloc[:, [col_index]] <span class="co"># as a DataFrame</span></span>
+<span id="cb42-15"><a href="#cb42-15" tabindex="-1"></a></span>
+<span id="cb42-16"><a href="#cb42-16" tabindex="-1"></a><span class="co"># using a mask</span></span>
+<span id="cb42-17"><a href="#cb42-17" tabindex="-1"></a>data.T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
 </div>
 <p>2. Access a single row:</p>
 <div class="codewrapper sourceCode" id="cb43">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
-<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
-<span id="cb43-3"><a href="#cb43-3" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]] <span class="co"># as a DataFrame</span></span>
-<span id="cb43-4"><a href="#cb43-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb43-5"><a href="#cb43-5" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb43-6"><a href="#cb43-6" aria-hidden="true" tabindex="-1"></a>data.T[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
-<span id="cb43-7"><a href="#cb43-7" aria-hidden="true" tabindex="-1"></a>data.T[[<span class="st">"row_name"</span>]].T <span class="co"># as a DataFrame</span></span>
-<span id="cb43-8"><a href="#cb43-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb43-9"><a href="#cb43-9" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb43-10"><a href="#cb43-10" aria-hidden="true" tabindex="-1"></a>data.iloc[row_index]   <span class="co"># as a Series</span></span>
-<span id="cb43-11"><a href="#cb43-11" aria-hidden="true" tabindex="-1"></a>data.iloc[[row_index]]   <span class="co"># as a DataFrame</span></span>
-<span id="cb43-12"><a href="#cb43-12" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb43-13"><a href="#cb43-13" aria-hidden="true" tabindex="-1"></a><span class="co"># using mask</span></span>
-<span id="cb43-14"><a href="#cb43-14" aria-hidden="true" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" tabindex="-1"></a><span class="co"># by name using .loc</span></span>
+<span id="cb43-2"><a href="#cb43-2" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
+<span id="cb43-3"><a href="#cb43-3" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]] <span class="co"># as a DataFrame</span></span>
+<span id="cb43-4"><a href="#cb43-4" tabindex="-1"></a></span>
+<span id="cb43-5"><a href="#cb43-5" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb43-6"><a href="#cb43-6" tabindex="-1"></a>data.T[<span class="st">"row_name"</span>] <span class="co"># as a Series</span></span>
+<span id="cb43-7"><a href="#cb43-7" tabindex="-1"></a>data.T[[<span class="st">"row_name"</span>]].T <span class="co"># as a DataFrame</span></span>
+<span id="cb43-8"><a href="#cb43-8" tabindex="-1"></a></span>
+<span id="cb43-9"><a href="#cb43-9" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb43-10"><a href="#cb43-10" tabindex="-1"></a>data.iloc[row_index]   <span class="co"># as a Series</span></span>
+<span id="cb43-11"><a href="#cb43-11" tabindex="-1"></a>data.iloc[[row_index]]   <span class="co"># as a DataFrame</span></span>
+<span id="cb43-12"><a href="#cb43-12" tabindex="-1"></a></span>
+<span id="cb43-13"><a href="#cb43-13" tabindex="-1"></a><span class="co"># using mask</span></span>
+<span id="cb43-14"><a href="#cb43-14" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>]</span></code></pre>
 </div>
 <p>3. Access an individual DataFrame element:</p>
 <div class="codewrapper sourceCode" id="cb44">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by column/row names</span></span>
-<span id="cb44-2"><a href="#cb44-2" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"column_name"</span>][<span class="st">"row_name"</span>]         <span class="co"># as a Series</span></span>
-<span id="cb44-3"><a href="#cb44-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-4"><a href="#cb44-4" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb44-5"><a href="#cb44-5" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
-<span id="cb44-6"><a href="#cb44-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-7"><a href="#cb44-7" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>][<span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
-<span id="cb44-8"><a href="#cb44-8" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb44-9"><a href="#cb44-9" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][[<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame</span></span>
-<span id="cb44-10"><a href="#cb44-10" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-11"><a href="#cb44-11" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, <span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
-<span id="cb44-12"><a href="#cb44-12" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], <span class="st">"col_name"</span>]  <span class="co"># as a Series. Preserves index. Column name is moved to `.name`.</span></span>
-<span id="cb44-13"><a href="#cb44-13" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, [<span class="st">"col_name"</span>]]  <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
-<span id="cb44-14"><a href="#cb44-14" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], [<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
-<span id="cb44-15"><a href="#cb44-15" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-16"><a href="#cb44-16" aria-hidden="true" tabindex="-1"></a><span class="co"># by column/row names: Dot notation</span></span>
-<span id="cb44-17"><a href="#cb44-17" aria-hidden="true" tabindex="-1"></a>data.col_name.row_name</span>
-<span id="cb44-18"><a href="#cb44-18" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-19"><a href="#cb44-19" aria-hidden="true" tabindex="-1"></a><span class="co"># by column/row indices</span></span>
-<span id="cb44-20"><a href="#cb44-20" aria-hidden="true" tabindex="-1"></a>data.iloc[row_index, col_index] <span class="co"># as a value</span></span>
-<span id="cb44-21"><a href="#cb44-21" aria-hidden="true" tabindex="-1"></a>data.iloc[[row_index], col_index] <span class="co"># as a Series. Preserves index. Column name is moved to `.name`</span></span>
-<span id="cb44-22"><a href="#cb44-22" aria-hidden="true" tabindex="-1"></a>data.iloc[row_index, [col_index]] <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
-<span id="cb44-23"><a href="#cb44-23" aria-hidden="true" tabindex="-1"></a>data.iloc[[row_index], [col_index]] <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
-<span id="cb44-24"><a href="#cb44-24" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-25"><a href="#cb44-25" aria-hidden="true" tabindex="-1"></a><span class="co"># column name + row index</span></span>
-<span id="cb44-26"><a href="#cb44-26" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"col_name"</span>][row_index]</span>
-<span id="cb44-27"><a href="#cb44-27" aria-hidden="true" tabindex="-1"></a>data.col_name[row_index]</span>
-<span id="cb44-28"><a href="#cb44-28" aria-hidden="true" tabindex="-1"></a>data[<span class="st">"col_name"</span>].iloc[row_index]</span>
-<span id="cb44-29"><a href="#cb44-29" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-30"><a href="#cb44-30" aria-hidden="true" tabindex="-1"></a><span class="co"># column index + row name</span></span>
-<span id="cb44-31"><a href="#cb44-31" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col_index]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
-<span id="cb44-32"><a href="#cb44-32" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col_index]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
-<span id="cb44-33"><a href="#cb44-33" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb44-34"><a href="#cb44-34" aria-hidden="true" tabindex="-1"></a><span class="co"># using masks</span></span>
-<span id="cb44-35"><a href="#cb44-35" aria-hidden="true" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>].T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" tabindex="-1"></a><span class="co"># by column/row names</span></span>
+<span id="cb44-2"><a href="#cb44-2" tabindex="-1"></a>data[<span class="st">"column_name"</span>][<span class="st">"row_name"</span>]         <span class="co"># as a Series</span></span>
+<span id="cb44-3"><a href="#cb44-3" tabindex="-1"></a></span>
+<span id="cb44-4"><a href="#cb44-4" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb44-5"><a href="#cb44-5" tabindex="-1"></a>data[[<span class="st">"col_name"</span>]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
+<span id="cb44-6"><a href="#cb44-6" tabindex="-1"></a></span>
+<span id="cb44-7"><a href="#cb44-7" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>][<span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
+<span id="cb44-8"><a href="#cb44-8" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][<span class="st">"col_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb44-9"><a href="#cb44-9" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>]][[<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame</span></span>
+<span id="cb44-10"><a href="#cb44-10" tabindex="-1"></a></span>
+<span id="cb44-11"><a href="#cb44-11" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, <span class="st">"col_name"</span>]  <span class="co"># as a value</span></span>
+<span id="cb44-12"><a href="#cb44-12" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], <span class="st">"col_name"</span>]  <span class="co"># as a Series. Preserves index. Column name is moved to `.name`.</span></span>
+<span id="cb44-13"><a href="#cb44-13" tabindex="-1"></a>data.loc[<span class="st">"row_name"</span>, [<span class="st">"col_name"</span>]]  <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
+<span id="cb44-14"><a href="#cb44-14" tabindex="-1"></a>data.loc[[<span class="st">"row_name"</span>], [<span class="st">"col_name"</span>]]  <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
+<span id="cb44-15"><a href="#cb44-15" tabindex="-1"></a></span>
+<span id="cb44-16"><a href="#cb44-16" tabindex="-1"></a><span class="co"># by column/row names: Dot notation</span></span>
+<span id="cb44-17"><a href="#cb44-17" tabindex="-1"></a>data.col_name.row_name</span>
+<span id="cb44-18"><a href="#cb44-18" tabindex="-1"></a></span>
+<span id="cb44-19"><a href="#cb44-19" tabindex="-1"></a><span class="co"># by column/row indices</span></span>
+<span id="cb44-20"><a href="#cb44-20" tabindex="-1"></a>data.iloc[row_index, col_index] <span class="co"># as a value</span></span>
+<span id="cb44-21"><a href="#cb44-21" tabindex="-1"></a>data.iloc[[row_index], col_index] <span class="co"># as a Series. Preserves index. Column name is moved to `.name`</span></span>
+<span id="cb44-22"><a href="#cb44-22" tabindex="-1"></a>data.iloc[row_index, [col_index]] <span class="co"># as a Series. Index is moved to `.name.` Sets index to column name.</span></span>
+<span id="cb44-23"><a href="#cb44-23" tabindex="-1"></a>data.iloc[[row_index], [col_index]] <span class="co"># as a DataFrame (preserves original index and column name)</span></span>
+<span id="cb44-24"><a href="#cb44-24" tabindex="-1"></a></span>
+<span id="cb44-25"><a href="#cb44-25" tabindex="-1"></a><span class="co"># column name + row index</span></span>
+<span id="cb44-26"><a href="#cb44-26" tabindex="-1"></a>data[<span class="st">"col_name"</span>][row_index]</span>
+<span id="cb44-27"><a href="#cb44-27" tabindex="-1"></a>data.col_name[row_index]</span>
+<span id="cb44-28"><a href="#cb44-28" tabindex="-1"></a>data[<span class="st">"col_name"</span>].iloc[row_index]</span>
+<span id="cb44-29"><a href="#cb44-29" tabindex="-1"></a></span>
+<span id="cb44-30"><a href="#cb44-30" tabindex="-1"></a><span class="co"># column index + row name</span></span>
+<span id="cb44-31"><a href="#cb44-31" tabindex="-1"></a>data.iloc[:, [col_index]].loc[<span class="st">"row_name"</span>]  <span class="co"># as a Series</span></span>
+<span id="cb44-32"><a href="#cb44-32" tabindex="-1"></a>data.iloc[:, [col_index]].loc[[<span class="st">"row_name"</span>]]  <span class="co"># as a DataFrame</span></span>
+<span id="cb44-33"><a href="#cb44-33" tabindex="-1"></a></span>
+<span id="cb44-34"><a href="#cb44-34" tabindex="-1"></a><span class="co"># using masks</span></span>
+<span id="cb44-35"><a href="#cb44-35" tabindex="-1"></a>data[data.index <span class="op">==</span> <span class="st">"row_name"</span>].T[data.T.index <span class="op">==</span> <span class="st">"col_name"</span>].T</span></code></pre>
 </div>
 <p>4. Access several columns:</p>
 <div class="codewrapper sourceCode" id="cb45">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb45-1"><a href="#cb45-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb45-2"><a href="#cb45-2" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
-<span id="cb45-3"><a href="#cb45-3" aria-hidden="true" tabindex="-1"></a>data.loc[:, [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
-<span id="cb45-4"><a href="#cb45-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb45-5"><a href="#cb45-5" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb45-6"><a href="#cb45-6" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb45-1"><a href="#cb45-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb45-2"><a href="#cb45-2" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
+<span id="cb45-3"><a href="#cb45-3" tabindex="-1"></a>data.loc[:, [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
+<span id="cb45-4"><a href="#cb45-4" tabindex="-1"></a></span>
+<span id="cb45-5"><a href="#cb45-5" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb45-6"><a href="#cb45-6" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]]</span></code></pre>
 </div>
 <p>5. Access several rows</p>
 <div class="codewrapper sourceCode" id="cb46">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb46-2"><a href="#cb46-2" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span>
-<span id="cb46-3"><a href="#cb46-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb46-4"><a href="#cb46-4" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb46-5"><a href="#cb46-5" aria-hidden="true" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index]]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb46-2"><a href="#cb46-2" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span>
+<span id="cb46-3"><a href="#cb46-3" tabindex="-1"></a></span>
+<span id="cb46-4"><a href="#cb46-4" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb46-5"><a href="#cb46-5" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index]]</span></code></pre>
 </div>
 <p>6. Access a subset of specific rows and columns</p>
 <div class="codewrapper sourceCode" id="cb47">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb47-1"><a href="#cb47-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by names</span></span>
-<span id="cb47-2"><a href="#cb47-2" aria-hidden="true" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>], [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
-<span id="cb47-3"><a href="#cb47-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb47-4"><a href="#cb47-4" aria-hidden="true" tabindex="-1"></a><span class="co"># by indices</span></span>
-<span id="cb47-5"><a href="#cb47-5" aria-hidden="true" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index], [col1_index, col2_index, col3_index]]</span>
-<span id="cb47-6"><a href="#cb47-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb47-7"><a href="#cb47-7" aria-hidden="true" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
-<span id="cb47-8"><a href="#cb47-8" aria-hidden="true" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]].iloc[[row1_index, row2_index, row3_index]]</span>
-<span id="cb47-9"><a href="#cb47-9" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb47-10"><a href="#cb47-10" aria-hidden="true" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
-<span id="cb47-11"><a href="#cb47-11" aria-hidden="true" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]].loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb47-1"><a href="#cb47-1" tabindex="-1"></a><span class="co"># by names</span></span>
+<span id="cb47-2"><a href="#cb47-2" tabindex="-1"></a>data.loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>], [<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]]</span>
+<span id="cb47-3"><a href="#cb47-3" tabindex="-1"></a></span>
+<span id="cb47-4"><a href="#cb47-4" tabindex="-1"></a><span class="co"># by indices</span></span>
+<span id="cb47-5"><a href="#cb47-5" tabindex="-1"></a>data.iloc[[row1_index, row2_index, row3_index], [col1_index, col2_index, col3_index]]</span>
+<span id="cb47-6"><a href="#cb47-6" tabindex="-1"></a></span>
+<span id="cb47-7"><a href="#cb47-7" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
+<span id="cb47-8"><a href="#cb47-8" tabindex="-1"></a>data[[<span class="st">"col1"</span>, <span class="st">"col2"</span>, <span class="st">"col3"</span>]].iloc[[row1_index, row2_index, row3_index]]</span>
+<span id="cb47-9"><a href="#cb47-9" tabindex="-1"></a></span>
+<span id="cb47-10"><a href="#cb47-10" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
+<span id="cb47-11"><a href="#cb47-11" tabindex="-1"></a>data.iloc[:, [col1_index, col2_index, col3_index]].loc[[<span class="st">"row1"</span>, <span class="st">"row2"</span>, <span class="st">"row3"</span>]]</span></code></pre>
 </div>
 <p>7. Access a subset of row and column ranges</p>
 <div class="codewrapper sourceCode" id="cb48">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" aria-hidden="true" tabindex="-1"></a><span class="co"># by name</span></span>
-<span id="cb48-2"><a href="#cb48-2" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>, <span class="st">"col1"</span>:<span class="st">"col2"</span>]</span>
-<span id="cb48-3"><a href="#cb48-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb48-4"><a href="#cb48-4" aria-hidden="true" tabindex="-1"></a><span class="co"># by index</span></span>
-<span id="cb48-5"><a href="#cb48-5" aria-hidden="true" tabindex="-1"></a>data.iloc[row1_index:row2_index, col1_index:col2_index]</span>
-<span id="cb48-6"><a href="#cb48-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb48-7"><a href="#cb48-7" aria-hidden="true" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
-<span id="cb48-8"><a href="#cb48-8" aria-hidden="true" tabindex="-1"></a>data.loc[:, <span class="st">"col1_name"</span>:<span class="st">"col2_name"</span>].iloc[row1_index:row2_index]</span>
-<span id="cb48-9"><a href="#cb48-9" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb48-10"><a href="#cb48-10" aria-hidden="true" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
-<span id="cb48-11"><a href="#cb48-11" aria-hidden="true" tabindex="-1"></a>data.iloc[:, col1_index:col2_index].loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" tabindex="-1"></a><span class="co"># by name</span></span>
+<span id="cb48-2"><a href="#cb48-2" tabindex="-1"></a>data.loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>, <span class="st">"col1"</span>:<span class="st">"col2"</span>]</span>
+<span id="cb48-3"><a href="#cb48-3" tabindex="-1"></a></span>
+<span id="cb48-4"><a href="#cb48-4" tabindex="-1"></a><span class="co"># by index</span></span>
+<span id="cb48-5"><a href="#cb48-5" tabindex="-1"></a>data.iloc[row1_index:row2_index, col1_index:col2_index]</span>
+<span id="cb48-6"><a href="#cb48-6" tabindex="-1"></a></span>
+<span id="cb48-7"><a href="#cb48-7" tabindex="-1"></a><span class="co"># column names + row indices</span></span>
+<span id="cb48-8"><a href="#cb48-8" tabindex="-1"></a>data.loc[:, <span class="st">"col1_name"</span>:<span class="st">"col2_name"</span>].iloc[row1_index:row2_index]</span>
+<span id="cb48-9"><a href="#cb48-9" tabindex="-1"></a></span>
+<span id="cb48-10"><a href="#cb48-10" tabindex="-1"></a><span class="co"># column indices + row names</span></span>
+<span id="cb48-11"><a href="#cb48-11" tabindex="-1"></a>data.iloc[:, col1_index:col2_index].loc[<span class="st">"row1"</span>:<span class="st">"row2"</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -5298,22 +5299,22 @@ <h3 class="callout-title">Exploring available methods using the<code>dir()</code
 <div class="codewrapper sourceCode" id="cb49">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb49-1"><a href="#cb49-1" aria-hidden="true" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>   <span class="co"># creation of a string object </span></span>
-<span id="cb49-2"><a href="#cb49-2" aria-hidden="true" tabindex="-1"></a><span class="bu">dir</span>(my_string)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb49-1"><a href="#cb49-1" tabindex="-1"></a>my_string <span class="op">=</span> <span class="st">'Hello world!'</span>   <span class="co"># creation of a string object </span></span>
+<span id="cb49-2"><a href="#cb49-2" tabindex="-1"></a><span class="bu">dir</span>(my_string)</span></code></pre>
 </div>
 <p>This command returns:</p>
 <div class="codewrapper sourceCode" id="cb50">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb50-1"><a href="#cb50-1" aria-hidden="true" tabindex="-1"></a>[<span class="st">'__add__'</span>,</span>
-<span id="cb50-2"><a href="#cb50-2" aria-hidden="true" tabindex="-1"></a>...</span>
-<span id="cb50-3"><a href="#cb50-3" aria-hidden="true" tabindex="-1"></a><span class="st">'__subclasshook__'</span>,</span>
-<span id="cb50-4"><a href="#cb50-4" aria-hidden="true" tabindex="-1"></a><span class="st">'capitalize'</span>,</span>
-<span id="cb50-5"><a href="#cb50-5" aria-hidden="true" tabindex="-1"></a><span class="st">'casefold'</span>,</span>
-<span id="cb50-6"><a href="#cb50-6" aria-hidden="true" tabindex="-1"></a><span class="st">'center'</span>,</span>
-<span id="cb50-7"><a href="#cb50-7" aria-hidden="true" tabindex="-1"></a>...</span>
-<span id="cb50-8"><a href="#cb50-8" aria-hidden="true" tabindex="-1"></a><span class="st">'upper'</span>,</span>
-<span id="cb50-9"><a href="#cb50-9" aria-hidden="true" tabindex="-1"></a><span class="st">'zfill'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb50-1"><a href="#cb50-1" tabindex="-1"></a>[<span class="st">'__add__'</span>,</span>
+<span id="cb50-2"><a href="#cb50-2" tabindex="-1"></a>...</span>
+<span id="cb50-3"><a href="#cb50-3" tabindex="-1"></a><span class="st">'__subclasshook__'</span>,</span>
+<span id="cb50-4"><a href="#cb50-4" tabindex="-1"></a><span class="st">'capitalize'</span>,</span>
+<span id="cb50-5"><a href="#cb50-5" tabindex="-1"></a><span class="st">'casefold'</span>,</span>
+<span id="cb50-6"><a href="#cb50-6" tabindex="-1"></a><span class="st">'center'</span>,</span>
+<span id="cb50-7"><a href="#cb50-7" tabindex="-1"></a>...</span>
+<span id="cb50-8"><a href="#cb50-8" tabindex="-1"></a><span class="st">'upper'</span>,</span>
+<span id="cb50-9"><a href="#cb50-9" tabindex="-1"></a><span class="st">'zfill'</span>]</span></code></pre>
 </div>
 <p>You can use <code>help()</code> or <kbd>Shift</kbd>+<kbd>Tab</kbd> to
 get more information about what these methods do.</p>
@@ -5329,14 +5330,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
 <div class="accordion-body">
 <p>Among many choices, <code>dir()</code> lists the
 <code>median()</code> function as a possibility. Thus,</p>
 <div class="codewrapper sourceCode" id="cb51">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb51-1"><a href="#cb51-1" aria-hidden="true" tabindex="-1"></a>data.median()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb51-1"><a href="#cb51-1" tabindex="-1"></a>data.median()</span></code></pre>
 </div>
 </div>
 </div>
@@ -5427,7 +5428,7 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span></code></pre>
 </div>
 <ul>
 <li>Simple plots are then (fairly) simple to create.</li>
@@ -5435,19 +5436,19 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a>time <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>]</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>position <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">100</span>, <span class="dv">200</span>, <span class="dv">300</span>]</span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a>plt.plot(time, position)</span>
-<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a>plt.xlabel(<span class="st">'Time (hr)'</span>)</span>
-<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'Position (km)'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a>time <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>]</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a>position <span class="op">=</span> [<span class="dv">0</span>, <span class="dv">100</span>, <span class="dv">200</span>, <span class="dv">300</span>]</span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a></span>
+<span id="cb2-4"><a href="#cb2-4" tabindex="-1"></a>plt.plot(time, position)</span>
+<span id="cb2-5"><a href="#cb2-5" tabindex="-1"></a>plt.xlabel(<span class="st">'Time (hr)'</span>)</span>
+<span id="cb2-6"><a href="#cb2-6" tabindex="-1"></a>plt.ylabel(<span class="st">'Position (km)'</span>)</span></code></pre>
 </div>
-<figure><img src="../fig/9_simple_position_time_plot.svg" alt="Simple Position-Time Plot" class="figure mx-auto d-block"></figure><div id="display-all-open-figures" class="callout callout">
+<figure><img src="../fig/9_simple_position_time_plot.svg" alt="Simple Position-Time Plot" class="figure mx-auto d-block"></figure><div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="display-all-open-figures" class="callout-inner">
-<h3 class="callout-title">Display All Open Figures<a class="anchor" aria-label="anchor" href="#display-all-open-figures"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="display-all-open-figures">Display All Open Figures<a class="anchor" aria-label="anchor" href="#display-all-open-figures"></a>
 </h3>
 <div class="callout-content">
 <p>In our Jupyter Notebook example, running the cell should generate the
@@ -5460,7 +5461,7 @@ <h3 class="callout-title">Display All Open Figures<a class="anchor" aria-label="
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>plt.show()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a>plt.show()</span></code></pre>
 </div>
 <p>This command can also be used within a Notebook - for instance, to
 display multiple figures if several are created by a single cell.</p>
@@ -5484,23 +5485,23 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-5"><a href="#cb4-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Extract year from last 4 characters of each column name</span></span>
-<span id="cb4-6"><a href="#cb4-6" aria-hidden="true" tabindex="-1"></a><span class="co"># The current column names are structured as 'gdpPercap_(year)', </span></span>
-<span id="cb4-7"><a href="#cb4-7" aria-hidden="true" tabindex="-1"></a><span class="co"># so we want to keep the (year) part only for clarity when plotting GDP vs. years</span></span>
-<span id="cb4-8"><a href="#cb4-8" aria-hidden="true" tabindex="-1"></a><span class="co"># To do this we use replace(), which removes from the string the characters stated in the argument</span></span>
-<span id="cb4-9"><a href="#cb4-9" aria-hidden="true" tabindex="-1"></a><span class="co"># This method works on strings, so we use replace() from Pandas Series.str vectorized string functions</span></span>
-<span id="cb4-10"><a href="#cb4-10" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-11"><a href="#cb4-11" aria-hidden="true" tabindex="-1"></a>years <span class="op">=</span> data.columns.<span class="bu">str</span>.replace(<span class="st">'gdpPercap_'</span>, <span class="st">''</span>)</span>
-<span id="cb4-12"><a href="#cb4-12" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-13"><a href="#cb4-13" aria-hidden="true" tabindex="-1"></a><span class="co"># Convert year values to integers, saving results back to dataframe</span></span>
-<span id="cb4-14"><a href="#cb4-14" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-15"><a href="#cb4-15" aria-hidden="true" tabindex="-1"></a>data.columns <span class="op">=</span> years.astype(<span class="bu">int</span>)</span>
-<span id="cb4-16"><a href="#cb4-16" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-17"><a href="#cb4-17" aria-hidden="true" tabindex="-1"></a>data.loc[<span class="st">'Australia'</span>].plot()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a></span>
+<span id="cb4-3"><a href="#cb4-3" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_oceania.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb4-4"><a href="#cb4-4" tabindex="-1"></a></span>
+<span id="cb4-5"><a href="#cb4-5" tabindex="-1"></a><span class="co"># Extract year from last 4 characters of each column name</span></span>
+<span id="cb4-6"><a href="#cb4-6" tabindex="-1"></a><span class="co"># The current column names are structured as 'gdpPercap_(year)', </span></span>
+<span id="cb4-7"><a href="#cb4-7" tabindex="-1"></a><span class="co"># so we want to keep the (year) part only for clarity when plotting GDP vs. years</span></span>
+<span id="cb4-8"><a href="#cb4-8" tabindex="-1"></a><span class="co"># To do this we use replace(), which removes from the string the characters stated in the argument</span></span>
+<span id="cb4-9"><a href="#cb4-9" tabindex="-1"></a><span class="co"># This method works on strings, so we use replace() from Pandas Series.str vectorized string functions</span></span>
+<span id="cb4-10"><a href="#cb4-10" tabindex="-1"></a></span>
+<span id="cb4-11"><a href="#cb4-11" tabindex="-1"></a>years <span class="op">=</span> data.columns.<span class="bu">str</span>.replace(<span class="st">'gdpPercap_'</span>, <span class="st">''</span>)</span>
+<span id="cb4-12"><a href="#cb4-12" tabindex="-1"></a></span>
+<span id="cb4-13"><a href="#cb4-13" tabindex="-1"></a><span class="co"># Convert year values to integers, saving results back to dataframe</span></span>
+<span id="cb4-14"><a href="#cb4-14" tabindex="-1"></a></span>
+<span id="cb4-15"><a href="#cb4-15" tabindex="-1"></a>data.columns <span class="op">=</span> years.astype(<span class="bu">int</span>)</span>
+<span id="cb4-16"><a href="#cb4-16" tabindex="-1"></a></span>
+<span id="cb4-17"><a href="#cb4-17" tabindex="-1"></a>data.loc[<span class="st">'Australia'</span>].plot()</span></code></pre>
 </div>
 <figure><img src="../fig/9_gdp_australia.svg" alt="GDP plot for Australia" class="figure mx-auto d-block"></figure></section><section id="select-and-transform-data-then-plot-it."><h2 class="section-heading">Select and transform data, then plot it.<a class="anchor" aria-label="anchor" href="#select-and-transform-data-then-plot-it."></a>
 </h2>
@@ -5513,8 +5514,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>data.T.plot()</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>data.T.plot()</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
 </div>
 <figure><img src="../fig/9_gdp_australia_nz.svg" alt="GDP plot for Australia and New Zealand" class="figure mx-auto d-block"></figure></section><section id="many-styles-of-plot-are-available."><h2 class="section-heading">Many styles of plot are available.<a class="anchor" aria-label="anchor" href="#many-styles-of-plot-are-available."></a>
 </h2>
@@ -5525,9 +5526,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>plt.style.use(<span class="st">'ggplot'</span>)</span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a>data.T.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
-<span id="cb6-3"><a href="#cb6-3" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a>plt.style.use(<span class="st">'ggplot'</span>)</span>
+<span id="cb6-2"><a href="#cb6-2" tabindex="-1"></a>data.T.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
+<span id="cb6-3"><a href="#cb6-3" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita'</span>)</span></code></pre>
 </div>
 <figure><img src="../fig/9_gdp_bar.svg" alt="GDP barplot for Australia" class="figure mx-auto d-block"></figure></section><section id="data-can-also-be-plotted-by-calling-the-matplotlib-plot-function-directly."><h2 class="section-heading">Data can also be plotted by calling the <code>matplotlib</code>
 <code>plot</code> function directly.<a class="anchor" aria-label="anchor" href="#data-can-also-be-plotted-by-calling-the-matplotlib-plot-function-directly."></a>
@@ -5545,10 +5546,10 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>years <span class="op">=</span> data.columns</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'g--'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>years <span class="op">=</span> data.columns</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a></span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'g--'</span>)</span></code></pre>
 </div>
 <figure><img src="../fig/9_gdp_australia_formatted.svg" alt="GDP formatted plot for Australia" class="figure mx-auto d-block"></figure></section><section id="can-plot-many-sets-of-data-together."><h2 class="section-heading">Can plot many sets of data together.<a class="anchor" aria-label="anchor" href="#can-plot-many-sets-of-data-together."></a>
 </h2>
@@ -5556,25 +5557,25 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Select two countries' worth of data.</span></span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
-<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a>gdp_nz <span class="op">=</span> data.loc[<span class="st">'New Zealand'</span>]</span>
-<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb8-5"><a href="#cb8-5" aria-hidden="true" tabindex="-1"></a><span class="co"># Plot with differently-colored markers.</span></span>
-<span id="cb8-6"><a href="#cb8-6" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'b-'</span>, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
-<span id="cb8-7"><a href="#cb8-7" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_nz, <span class="st">'g-'</span>, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span>
-<span id="cb8-8"><a href="#cb8-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb8-9"><a href="#cb8-9" aria-hidden="true" tabindex="-1"></a><span class="co"># Create legend.</span></span>
-<span id="cb8-10"><a href="#cb8-10" aria-hidden="true" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'upper left'</span>)</span>
-<span id="cb8-11"><a href="#cb8-11" aria-hidden="true" tabindex="-1"></a>plt.xlabel(<span class="st">'Year'</span>)</span>
-<span id="cb8-12"><a href="#cb8-12" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita ($)'</span>)</span></code></pre>
-</div>
-<div id="adding-a-legend" class="callout callout">
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="co"># Select two countries' worth of data.</span></span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a>gdp_australia <span class="op">=</span> data.loc[<span class="st">'Australia'</span>]</span>
+<span id="cb8-3"><a href="#cb8-3" tabindex="-1"></a>gdp_nz <span class="op">=</span> data.loc[<span class="st">'New Zealand'</span>]</span>
+<span id="cb8-4"><a href="#cb8-4" tabindex="-1"></a></span>
+<span id="cb8-5"><a href="#cb8-5" tabindex="-1"></a><span class="co"># Plot with differently-colored markers.</span></span>
+<span id="cb8-6"><a href="#cb8-6" tabindex="-1"></a>plt.plot(years, gdp_australia, <span class="st">'b-'</span>, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
+<span id="cb8-7"><a href="#cb8-7" tabindex="-1"></a>plt.plot(years, gdp_nz, <span class="st">'g-'</span>, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span>
+<span id="cb8-8"><a href="#cb8-8" tabindex="-1"></a></span>
+<span id="cb8-9"><a href="#cb8-9" tabindex="-1"></a><span class="co"># Create legend.</span></span>
+<span id="cb8-10"><a href="#cb8-10" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'upper left'</span>)</span>
+<span id="cb8-11"><a href="#cb8-11" tabindex="-1"></a>plt.xlabel(<span class="st">'Year'</span>)</span>
+<span id="cb8-12"><a href="#cb8-12" tabindex="-1"></a>plt.ylabel(<span class="st">'GDP per capita ($)'</span>)</span></code></pre>
+</div>
+<div id="callout2" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="adding-a-legend" class="callout-inner">
-<h3 class="callout-title">Adding a Legend<a class="anchor" aria-label="anchor" href="#adding-a-legend"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="adding-a-legend">Adding a Legend<a class="anchor" aria-label="anchor" href="#adding-a-legend"></a>
 </h3>
 <div class="callout-content">
 <p>Often when plotting multiple datasets on the same figure it is
@@ -5586,8 +5587,8 @@ <h3 class="callout-title">Adding a Legend<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_australia, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>plt.plot(years, gdp_nz, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>plt.plot(years, gdp_australia, label<span class="op">=</span><span class="st">'Australia'</span>)</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>plt.plot(years, gdp_nz, label<span class="op">=</span><span class="st">'New Zealand'</span>)</span></code></pre>
 </div>
 <ul>
 <li>Instruct <code>matplotlib</code> to create the legend.</li>
@@ -5595,7 +5596,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a>plt.legend()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a>plt.legend()</span></code></pre>
 </div>
 <p>By default matplotlib will attempt to place the legend in a suitable
 position. If you would rather specify a position this can be done with
@@ -5614,12 +5615,12 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>plt.scatter(gdp_australia, gdp_nz)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>plt.scatter(gdp_australia, gdp_nz)</span></code></pre>
 </div>
 <figure><img src="../fig/9_gdp_correlation_plt.svg" alt="GDP correlation using plt.scatter" class="figure mx-auto d-block"></figure><div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a>data.T.plot.scatter(x <span class="op">=</span> <span class="st">'Australia'</span>, y <span class="op">=</span> <span class="st">'New Zealand'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a>data.T.plot.scatter(x <span class="op">=</span> <span class="st">'Australia'</span>, y <span class="op">=</span> <span class="st">'New Zealand'</span>)</span></code></pre>
 </div>
 <figure><img src="../fig/9_gdp_correlation_data.svg" alt="GDP correlation using data.T.plot.scatter" class="figure mx-auto d-block"></figure><div id="minima-and-maxima" class="callout challenge">
 <div class="callout-square">
@@ -5635,11 +5636,11 @@ <h3 class="callout-title">Minima and Maxima<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a>data_europe.____.plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
-<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a>data_europe.____</span>
-<span id="cb13-4"><a href="#cb13-4" aria-hidden="true" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
-<span id="cb13-5"><a href="#cb13-5" aria-hidden="true" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a>data_europe.____.plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
+<span id="cb13-3"><a href="#cb13-3" tabindex="-1"></a>data_europe.____</span>
+<span id="cb13-4"><a href="#cb13-4" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
+<span id="cb13-5"><a href="#cb13-5" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -5649,16 +5650,16 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a>data_europe.<span class="bu">min</span>().plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a>data_europe.<span class="bu">max</span>().plot(label<span class="op">=</span><span class="st">'max'</span>)</span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>data_europe <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_europe.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a>data_europe.<span class="bu">min</span>().plot(label<span class="op">=</span><span class="st">'min'</span>)</span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a>data_europe.<span class="bu">max</span>().plot(label<span class="op">=</span><span class="st">'max'</span>)</span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a>plt.legend(loc<span class="op">=</span><span class="st">'best'</span>)</span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a>plt.xticks(rotation<span class="op">=</span><span class="dv">90</span>)</span></code></pre>
 </div>
 <figure><img src="../fig/9_minima_maxima_solution.png" alt="Minima Maxima Solution" class="figure mx-auto d-block"></figure>
 </div>
@@ -5685,13 +5686,13 @@ <h3 class="callout-title">Correlations<a class="anchor" aria-label="anchor" href
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>data_asia.describe().T.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'min'</span>, y<span class="op">=</span><span class="st">'max'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>data_asia.describe().T.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'min'</span>, y<span class="op">=</span><span class="st">'max'</span>)</span></code></pre>
 </div>
 <figure><img src="../fig/9_correlations_solution1.svg" alt="Correlations Solution 1" class="figure mx-auto d-block"></figure><p>No particular correlations can be seen between the minimum and
 maximum gdp values year on year. It seems the fortunes of asian
@@ -5714,10 +5715,10 @@ <h3 class="callout-title">Correlations<em>(continued)</em><a class="anchor" aria
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a>data_asia.<span class="bu">max</span>().plot()</span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmax())</span>
-<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmin())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a>data_asia.<span class="bu">max</span>().plot()</span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmax())</span>
+<span id="cb16-4"><a href="#cb16-4" tabindex="-1"></a><span class="bu">print</span>(data_asia.idxmin())</span></code></pre>
 </div>
 </div>
 </div>
@@ -5727,7 +5728,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
 <div class="accordion-body">
 <figure><img src="../fig/9_correlations_solution2.png" alt="Correlations Solution 2" class="figure mx-auto d-block"></figure><p>Seems the variability in this value is due to a sharp drop after
 1972. Some geopolitics at play perhaps? Given the dominance of oil
@@ -5751,9 +5752,9 @@ <h3 class="callout-title">More Correlations<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>data_all <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>data_all.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'gdpPercap_2007'</span>, y<span class="op">=</span><span class="st">'lifeExp_2007'</span>,</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a>              s<span class="op">=</span>data_all[<span class="st">'pop_2007'</span>]<span class="op">/</span><span class="fl">1e6</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>data_all <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>data_all.plot(kind<span class="op">=</span><span class="st">'scatter'</span>, x<span class="op">=</span><span class="st">'gdpPercap_2007'</span>, y<span class="op">=</span><span class="st">'lifeExp_2007'</span>,</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a>              s<span class="op">=</span>data_all[<span class="st">'pop_2007'</span>]<span class="op">/</span><span class="fl">1e6</span>)</span></code></pre>
 </div>
 <p>Using online help and other resources, explain what each argument to
 <code>plot</code> does.</p>
@@ -5765,7 +5766,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
 <div class="accordion-body">
 <figure><img src="../fig/9_more_correlations_solution.svg" alt="More Correlations Solution" class="figure mx-auto d-block"></figure><p>A good place to look is the documentation for the plot function -
 help(data_all.plot).</p>
@@ -5780,12 +5781,12 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </div>
 </div>
 </div>
-<div id="saving-your-plot-to-a-file" class="callout callout">
+<div id="callout3" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="saving-your-plot-to-a-file" class="callout-inner">
-<h3 class="callout-title">Saving your plot to a file<a class="anchor" aria-label="anchor" href="#saving-your-plot-to-a-file"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="saving-your-plot-to-a-file">Saving your plot to a file<a class="anchor" aria-label="anchor" href="#saving-your-plot-to-a-file"></a>
 </h3>
 <div class="callout-content">
 <p>If you are satisfied with the plot you see you may want to save it to
@@ -5795,7 +5796,7 @@ <h3 class="callout-title">Saving your plot to a file<a class="anchor" aria-label
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>plt.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>plt.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
 </div>
 <p>will save the current figure to the file <code>my_figure.png</code>.
 The file format will automatically be deduced from the file name
@@ -5814,19 +5815,19 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a>data.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>fig <span class="op">=</span> plt.gcf() <span class="co"># get current figure</span></span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a>fig.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a>data.plot(kind<span class="op">=</span><span class="st">'bar'</span>)</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>fig <span class="op">=</span> plt.gcf() <span class="co"># get current figure</span></span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a>fig.savefig(<span class="st">'my_figure.png'</span>)</span></code></pre>
 </div>
 </div>
 </div>
 </div>
-<div id="making-your-plots-accessible" class="callout callout">
+<div id="callout4" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="making-your-plots-accessible" class="callout-inner">
-<h3 class="callout-title">Making your plots accessible<a class="anchor" aria-label="anchor" href="#making-your-plots-accessible"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="making-your-plots-accessible">Making your plots accessible<a class="anchor" aria-label="anchor" href="#making-your-plots-accessible"></a>
 </h3>
 <div class="callout-content">
 <p>Whenever you are generating plots to go into a paper or a
@@ -5945,9 +5946,9 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>pressures <span class="op">=</span> [<span class="fl">0.273</span>, <span class="fl">0.275</span>, <span class="fl">0.277</span>, <span class="fl">0.275</span>, <span class="fl">0.276</span>]</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures:'</span>, pressures)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'length:'</span>, <span class="bu">len</span>(pressures))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>pressures <span class="op">=</span> [<span class="fl">0.273</span>, <span class="fl">0.275</span>, <span class="fl">0.277</span>, <span class="fl">0.275</span>, <span class="fl">0.276</span>]</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures:'</span>, pressures)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'length:'</span>, <span class="bu">len</span>(pressures))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5964,8 +5965,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth item of pressures:'</span>, pressures[<span class="dv">0</span>])</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'fourth item of pressures:'</span>, pressures[<span class="dv">4</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth item of pressures:'</span>, pressures[<span class="dv">0</span>])</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'fourth item of pressures:'</span>, pressures[<span class="dv">4</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -5983,8 +5984,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>pressures[<span class="dv">0</span>] <span class="op">=</span> <span class="fl">0.265</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures is now:'</span>, pressures)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>pressures[<span class="dv">0</span>] <span class="op">=</span> <span class="fl">0.265</span></span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'pressures is now:'</span>, pressures)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6001,10 +6002,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is initially:'</span>, primes)</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>primes.append(<span class="dv">7</span>)</span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has become:'</span>, primes)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is initially:'</span>, primes)</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a>primes.append(<span class="dv">7</span>)</span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has become:'</span>, primes)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6036,13 +6037,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>teen_primes <span class="op">=</span> [<span class="dv">11</span>, <span class="dv">13</span>, <span class="dv">17</span>, <span class="dv">19</span>]</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>middle_aged_primes <span class="op">=</span> [<span class="dv">37</span>, <span class="dv">41</span>, <span class="dv">43</span>, <span class="dv">47</span>]</span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is currently:'</span>, primes)</span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a>primes.extend(teen_primes)</span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has now become:'</span>, primes)</span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a>primes.append(middle_aged_primes)</span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has finally become:'</span>, primes)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>teen_primes <span class="op">=</span> [<span class="dv">11</span>, <span class="dv">13</span>, <span class="dv">17</span>, <span class="dv">19</span>]</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>middle_aged_primes <span class="op">=</span> [<span class="dv">37</span>, <span class="dv">41</span>, <span class="dv">43</span>, <span class="dv">47</span>]</span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes is currently:'</span>, primes)</span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a>primes.extend(teen_primes)</span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has now become:'</span>, primes)</span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a>primes.append(middle_aged_primes)</span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes has finally become:'</span>, primes)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6068,10 +6069,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>, <span class="dv">7</span>, <span class="dv">9</span>]</span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes before removing last item:'</span>, primes)</span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a><span class="kw">del</span> primes[<span class="dv">4</span>]</span>
-<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes after removing last item:'</span>, primes)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>, <span class="dv">7</span>, <span class="dv">9</span>]</span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes before removing last item:'</span>, primes)</span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a><span class="kw">del</span> primes[<span class="dv">4</span>]</span>
+<span id="cb11-4"><a href="#cb11-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'primes after removing last item:'</span>, primes)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6100,7 +6101,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>goals <span class="op">=</span> [<span class="dv">1</span>, <span class="st">'Create lists.'</span>, <span class="dv">2</span>, <span class="st">'Extract items from lists.'</span>, <span class="dv">3</span>, <span class="st">'Modify lists.'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>goals <span class="op">=</span> [<span class="dv">1</span>, <span class="st">'Create lists.'</span>, <span class="dv">2</span>, <span class="st">'Extract items from lists.'</span>, <span class="dv">3</span>, <span class="st">'Modify lists.'</span>]</span></code></pre>
 </div>
 </section><section id="character-strings-can-be-indexed-like-lists."><h2 class="section-heading">Character strings can be indexed like lists.<a class="anchor" aria-label="anchor" href="#character-strings-can-be-indexed-like-lists."></a>
 </h2>
@@ -6112,9 +6113,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'carbon'</span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth character:'</span>, element[<span class="dv">0</span>])</span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'third character:'</span>, element[<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'carbon'</span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'zeroth character:'</span>, element[<span class="dv">0</span>])</span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'third character:'</span>, element[<span class="dv">3</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6140,7 +6141,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>element[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'C'</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>element[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'C'</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6165,7 +6166,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'99th element of element is:'</span>, element[<span class="dv">99</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'99th element of element is:'</span>, element[<span class="dv">99</span>])</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6185,13 +6186,13 @@ <h3 class="callout-title">Fill in the Blanks<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> ____</span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>values.____(<span class="dv">1</span>)</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a>values.____(<span class="dv">3</span>)</span>
-<span id="cb20-4"><a href="#cb20-4" aria-hidden="true" tabindex="-1"></a>values.____(<span class="dv">5</span>)</span>
-<span id="cb20-5"><a href="#cb20-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
-<span id="cb20-6"><a href="#cb20-6" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> values[____]</span>
-<span id="cb20-7"><a href="#cb20-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>values <span class="op">=</span> ____</span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>values.____(<span class="dv">1</span>)</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a>values.____(<span class="dv">3</span>)</span>
+<span id="cb20-4"><a href="#cb20-4" tabindex="-1"></a>values.____(<span class="dv">5</span>)</span>
+<span id="cb20-5"><a href="#cb20-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
+<span id="cb20-6"><a href="#cb20-6" tabindex="-1"></a>values <span class="op">=</span> values[____]</span>
+<span id="cb20-7"><a href="#cb20-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6212,13 +6213,13 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> []</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>values.append(<span class="dv">1</span>)</span>
-<span id="cb22-3"><a href="#cb22-3" aria-hidden="true" tabindex="-1"></a>values.append(<span class="dv">3</span>)</span>
-<span id="cb22-4"><a href="#cb22-4" aria-hidden="true" tabindex="-1"></a>values.append(<span class="dv">5</span>)</span>
-<span id="cb22-5"><a href="#cb22-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
-<span id="cb22-6"><a href="#cb22-6" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> values[<span class="dv">1</span>:]</span>
-<span id="cb22-7"><a href="#cb22-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>values <span class="op">=</span> []</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>values.append(<span class="dv">1</span>)</span>
+<span id="cb22-3"><a href="#cb22-3" tabindex="-1"></a>values.append(<span class="dv">3</span>)</span>
+<span id="cb22-4"><a href="#cb22-4" tabindex="-1"></a>values.append(<span class="dv">5</span>)</span>
+<span id="cb22-5"><a href="#cb22-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'first time:'</span>, values)</span>
+<span id="cb22-6"><a href="#cb22-6" tabindex="-1"></a>values <span class="op">=</span> values[<span class="dv">1</span>:]</span>
+<span id="cb22-7"><a href="#cb22-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'second time:'</span>, values)</span></code></pre>
 </div>
 </div>
 </div>
@@ -6267,8 +6268,8 @@ <h3 class="callout-title">From Strings to Lists and Back<a class="anchor" aria-l
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'string to list:'</span>, <span class="bu">list</span>(<span class="st">'tin'</span>))</span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'list to string:'</span>, <span class="st">''</span>.join([<span class="st">'g'</span>, <span class="st">'o'</span>, <span class="st">'l'</span>, <span class="st">'d'</span>]))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'string to list:'</span>, <span class="bu">list</span>(<span class="st">'tin'</span>))</span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'list to string:'</span>, <span class="st">''</span>.join([<span class="st">'g'</span>, <span class="st">'o'</span>, <span class="st">'l'</span>, <span class="st">'d'</span>]))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6317,8 +6318,8 @@ <h3 class="callout-title">Working With the End<a class="anchor" aria-label="anch
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'helium'</span></span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'helium'</span></span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>How does Python interpret a negative index?</li>
@@ -6369,9 +6370,9 @@ <h3 class="callout-title">Stepping Through a List<a class="anchor" aria-label="a
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'fluorine'</span></span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="dv">2</span>])</span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'fluorine'</span></span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="dv">2</span>])</span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a><span class="bu">print</span>(element[::<span class="op">-</span><span class="dv">1</span>])</span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>If we write a slice as <code>low:high:stride</code>, what does
@@ -6393,8 +6394,8 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>furn</span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>eniroulf</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>furn</span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>eniroulf</span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>
@@ -6421,9 +6422,9 @@ <h3 class="callout-title">Slice Bounds<a class="anchor" aria-label="anchor" href
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'lithium'</span></span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[<span class="dv">0</span>:<span class="dv">20</span>])</span>
-<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>element <span class="op">=</span> <span class="st">'lithium'</span></span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a><span class="bu">print</span>(element[<span class="dv">0</span>:<span class="dv">20</span>])</span>
+<span id="cb28-3"><a href="#cb28-3" tabindex="-1"></a><span class="bu">print</span>(element[<span class="op">-</span><span class="dv">1</span>:<span class="dv">3</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -6461,18 +6462,18 @@ <h3 class="callout-title">Sort and Sorted<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program A</span></span>
-<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb30-3"><a href="#cb30-3" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">sorted</span>(letters)</span>
-<span id="cb30-4"><a href="#cb30-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a><span class="co"># Program A</span></span>
+<span id="cb30-2"><a href="#cb30-2" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb30-3"><a href="#cb30-3" tabindex="-1"></a>result <span class="op">=</span> <span class="bu">sorted</span>(letters)</span>
+<span id="cb30-4"><a href="#cb30-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program B</span></span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> letters.sort()</span>
-<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a><span class="co"># Program B</span></span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a>letters <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb31-3"><a href="#cb31-3" tabindex="-1"></a>result <span class="op">=</span> letters.sort()</span>
+<span id="cb31-4"><a href="#cb31-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'letters is'</span>, letters, <span class="st">'and result is'</span>, result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -6518,20 +6519,20 @@ <h3 class="callout-title">Copying (or Not)<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program A</span></span>
-<span id="cb34-2"><a href="#cb34-2" aria-hidden="true" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb34-3"><a href="#cb34-3" aria-hidden="true" tabindex="-1"></a>new <span class="op">=</span> old      <span class="co"># simple assignment</span></span>
-<span id="cb34-4"><a href="#cb34-4" aria-hidden="true" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
-<span id="cb34-5"><a href="#cb34-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a><span class="co"># Program A</span></span>
+<span id="cb34-2"><a href="#cb34-2" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb34-3"><a href="#cb34-3" tabindex="-1"></a>new <span class="op">=</span> old      <span class="co"># simple assignment</span></span>
+<span id="cb34-4"><a href="#cb34-4" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
+<span id="cb34-5"><a href="#cb34-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Program B</span></span>
-<span id="cb35-2"><a href="#cb35-2" aria-hidden="true" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
-<span id="cb35-3"><a href="#cb35-3" aria-hidden="true" tabindex="-1"></a>new <span class="op">=</span> old[:]   <span class="co"># assigning a slice</span></span>
-<span id="cb35-4"><a href="#cb35-4" aria-hidden="true" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
-<span id="cb35-5"><a href="#cb35-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a><span class="co"># Program B</span></span>
+<span id="cb35-2"><a href="#cb35-2" tabindex="-1"></a>old <span class="op">=</span> <span class="bu">list</span>(<span class="st">'gold'</span>)</span>
+<span id="cb35-3"><a href="#cb35-3" tabindex="-1"></a>new <span class="op">=</span> old[:]   <span class="co"># assigning a slice</span></span>
+<span id="cb35-4"><a href="#cb35-4" tabindex="-1"></a>new[<span class="dv">0</span>] <span class="op">=</span> <span class="st">'D'</span></span>
+<span id="cb35-5"><a href="#cb35-5" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'new is'</span>, new, <span class="st">'and old is'</span>, old)</span></code></pre>
 </div>
 </div>
 </div>
@@ -6641,8 +6642,8 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 <ul>
 <li>This <code>for</code> loop is equivalent to:</li>
@@ -6650,9 +6651,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">2</span>)</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">3</span>)</span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">2</span>)</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">3</span>)</span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a><span class="bu">print</span>(<span class="dv">5</span>)</span></code></pre>
 </div>
 <ul>
 <li>And the <code>for</code> loop’s output is:</li>
@@ -6671,8 +6672,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 <ul>
 <li>The collection, <code>[2, 3, 5]</code>, is what the loop is being
@@ -6703,8 +6704,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="bu">print</span>(number)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6717,8 +6718,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>firstName <span class="op">=</span> <span class="st">"Jon"</span></span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>  lastName <span class="op">=</span> <span class="st">"Smith"</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>firstName <span class="op">=</span> <span class="st">"Jon"</span></span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>  lastName <span class="op">=</span> <span class="st">"Smith"</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6745,8 +6746,8 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> kitten <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(kitten)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="cf">for</span> kitten <span class="kw">in</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]:</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>    <span class="bu">print</span>(kitten)</span></code></pre>
 </div>
 </section><section id="the-body-of-a-loop-can-contain-many-statements."><h2 class="section-heading">The body of a loop can contain many statements.<a class="anchor" aria-label="anchor" href="#the-body-of-a-loop-can-contain-many-statements."></a>
 </h2>
@@ -6758,11 +6759,11 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> p <span class="kw">in</span> primes:</span>
-<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>    squared <span class="op">=</span> p <span class="op">**</span> <span class="dv">2</span></span>
-<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a>    cubed <span class="op">=</span> p <span class="op">**</span> <span class="dv">3</span></span>
-<span id="cb10-5"><a href="#cb10-5" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(p, squared, cubed)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a>primes <span class="op">=</span> [<span class="dv">2</span>, <span class="dv">3</span>, <span class="dv">5</span>]</span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a><span class="cf">for</span> p <span class="kw">in</span> primes:</span>
+<span id="cb10-3"><a href="#cb10-3" tabindex="-1"></a>    squared <span class="op">=</span> p <span class="op">**</span> <span class="dv">2</span></span>
+<span id="cb10-4"><a href="#cb10-4" tabindex="-1"></a>    cubed <span class="op">=</span> p <span class="op">**</span> <span class="dv">3</span></span>
+<span id="cb10-5"><a href="#cb10-5" tabindex="-1"></a>    <span class="bu">print</span>(p, squared, cubed)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6794,9 +6795,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'a range is not a list: range(0, 3)'</span>)</span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>, <span class="dv">3</span>):</span>
-<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'a range is not a list: range(0, 3)'</span>)</span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>, <span class="dv">3</span>):</span>
+<span id="cb12-3"><a href="#cb12-3" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6821,11 +6822,11 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb14">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Sum the first 10 integers.</span></span>
-<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb14-4"><a href="#cb14-4" aria-hidden="true" tabindex="-1"></a>   total <span class="op">=</span> total <span class="op">+</span> (number <span class="op">+</span> <span class="dv">1</span>)</span>
-<span id="cb14-5"><a href="#cb14-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" tabindex="-1"></a><span class="co"># Sum the first 10 integers.</span></span>
+<span id="cb14-2"><a href="#cb14-2" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb14-3"><a href="#cb14-3" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb14-4"><a href="#cb14-4" tabindex="-1"></a>   total <span class="op">=</span> total <span class="op">+</span> (number <span class="op">+</span> <span class="dv">1</span>)</span>
+<span id="cb14-5"><a href="#cb14-5" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -6862,7 +6863,7 @@ <h3 class="callout-title">Classifying Errors<a class="anchor" aria-label="anchor
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>An IndentationError is a syntax error. Programs with syntax errors
 cannot be started. A program with a runtime error will start but an
@@ -6885,9 +6886,9 @@ <h3 class="callout-title">Tracing Execution<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> <span class="st">"tin"</span>:</span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> <span class="st">"tin"</span>:</span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="dv">1</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -6897,7 +6898,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <table class="table">
 <thead><tr class="header">
@@ -6952,11 +6953,11 @@ <h3 class="callout-title">Reversing a String<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> ____</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
-<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> ____</span>
-<span id="cb17-5"><a href="#cb17-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>result <span class="op">=</span> ____</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
+<span id="cb17-4"><a href="#cb17-4" tabindex="-1"></a>    result <span class="op">=</span> ____</span>
+<span id="cb17-5"><a href="#cb17-5" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -6966,16 +6967,16 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
-<span id="cb18-2"><a href="#cb18-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb18-3"><a href="#cb18-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
-<span id="cb18-4"><a href="#cb18-4" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> char <span class="op">+</span> result</span>
-<span id="cb18-5"><a href="#cb18-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>original <span class="op">=</span> <span class="st">"tin"</span></span>
+<span id="cb18-2"><a href="#cb18-2" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb18-3"><a href="#cb18-3" tabindex="-1"></a><span class="cf">for</span> char <span class="kw">in</span> original:</span>
+<span id="cb18-4"><a href="#cb18-4" tabindex="-1"></a>    result <span class="op">=</span> char <span class="op">+</span> result</span>
+<span id="cb18-5"><a href="#cb18-5" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -6994,11 +6995,11 @@ <h3 class="callout-title">Practice Accumulating<a class="anchor" aria-label="anc
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Total length of the strings in the list: ["red", "green", "blue"] =&gt; 12</span></span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb19-3"><a href="#cb19-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb19-4"><a href="#cb19-4" aria-hidden="true" tabindex="-1"></a>    ____ <span class="op">=</span> ____ <span class="op">+</span> <span class="bu">len</span>(word)</span>
-<span id="cb19-5"><a href="#cb19-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="co"># Total length of the strings in the list: ["red", "green", "blue"] =&gt; 12</span></span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb19-3"><a href="#cb19-3" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb19-4"><a href="#cb19-4" tabindex="-1"></a>    ____ <span class="op">=</span> ____ <span class="op">+</span> <span class="bu">len</span>(word)</span>
+<span id="cb19-5"><a href="#cb19-5" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7008,15 +7009,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution4" aria-expanded="false" aria-controls="collapseSolution4">
   <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 </button>
-<div id="collapseSolution4" class="accordion-collapse collapse" data-bs-parent="#accordionSolution4" aria-labelledby="headingSolution4">
+<div id="collapseSolution4" class="accordion-collapse collapse" aria-labelledby="headingSolution4" data-bs-parent="#accordionSolution4">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="bu">len</span>(word)</span>
-<span id="cb20-4"><a href="#cb20-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> <span class="bu">len</span>(word)</span>
+<span id="cb20-4"><a href="#cb20-4" tabindex="-1"></a><span class="bu">print</span>(total)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7033,11 +7034,11 @@ <h3 class="callout-title">Practice Accumulating<em>(continued)</em><a class="anc
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="co"># List of word lengths: ["red", "green", "blue"] =&gt; [3, 5, 4]</span></span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a>lengths <span class="op">=</span> ____</span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb21-4"><a href="#cb21-4" aria-hidden="true" tabindex="-1"></a>    lengths.____(____)</span>
-<span id="cb21-5"><a href="#cb21-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a><span class="co"># List of word lengths: ["red", "green", "blue"] =&gt; [3, 5, 4]</span></span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a>lengths <span class="op">=</span> ____</span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb21-4"><a href="#cb21-4" tabindex="-1"></a>    lengths.____(____)</span>
+<span id="cb21-5"><a href="#cb21-5" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7047,15 +7048,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution5" aria-expanded="false" aria-controls="collapseSolution5">
   <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 </button>
-<div id="collapseSolution5" class="accordion-collapse collapse" data-bs-parent="#accordionSolution5" aria-labelledby="headingSolution5">
+<div id="collapseSolution5" class="accordion-collapse collapse" aria-labelledby="headingSolution5" data-bs-parent="#accordionSolution5">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>lengths <span class="op">=</span> []</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb22-3"><a href="#cb22-3" aria-hidden="true" tabindex="-1"></a>    lengths.append(<span class="bu">len</span>(word))</span>
-<span id="cb22-4"><a href="#cb22-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>lengths <span class="op">=</span> []</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb22-3"><a href="#cb22-3" tabindex="-1"></a>    lengths.append(<span class="bu">len</span>(word))</span>
+<span id="cb22-4"><a href="#cb22-4" tabindex="-1"></a><span class="bu">print</span>(lengths)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7072,12 +7073,12 @@ <h3 class="callout-title">Practice Accumulating<em>(continued)</em><a class="anc
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Concatenate all words: ["red", "green", "blue"] =&gt; "redgreenblue"</span></span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
-<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> ____</span>
-<span id="cb23-4"><a href="#cb23-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> ____ <span class="kw">in</span> ____:</span>
-<span id="cb23-5"><a href="#cb23-5" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb23-6"><a href="#cb23-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="co"># Concatenate all words: ["red", "green", "blue"] =&gt; "redgreenblue"</span></span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
+<span id="cb23-3"><a href="#cb23-3" tabindex="-1"></a>result <span class="op">=</span> ____</span>
+<span id="cb23-4"><a href="#cb23-4" tabindex="-1"></a><span class="cf">for</span> ____ <span class="kw">in</span> ____:</span>
+<span id="cb23-5"><a href="#cb23-5" tabindex="-1"></a>    ____</span>
+<span id="cb23-6"><a href="#cb23-6" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7087,16 +7088,16 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution6" aria-expanded="false" aria-controls="collapseSolution6">
   <h4 class="accordion-header" id="headingSolution6">Show me the solution</h4>
 </button>
-<div id="collapseSolution6" class="accordion-collapse collapse" data-bs-parent="#accordionSolution6" aria-labelledby="headingSolution6">
+<div id="collapseSolution6" class="accordion-collapse collapse" aria-labelledby="headingSolution6" data-bs-parent="#accordionSolution6">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> words:</span>
-<span id="cb24-4"><a href="#cb24-4" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> result <span class="op">+</span> word</span>
-<span id="cb24-5"><a href="#cb24-5" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a>words <span class="op">=</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a>result <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb24-3"><a href="#cb24-3" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> words:</span>
+<span id="cb24-4"><a href="#cb24-4" tabindex="-1"></a>    result <span class="op">=</span> result <span class="op">+</span> word</span>
+<span id="cb24-5"><a href="#cb24-5" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7123,15 +7124,15 @@ <h3 class="callout-title">Practice Accumulating<em>(continued)</em><a class="anc
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution7" aria-expanded="false" aria-controls="collapseSolution7">
   <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 </button>
-<div id="collapseSolution7" class="accordion-collapse collapse" data-bs-parent="#accordionSolution7" aria-labelledby="headingSolution7">
+<div id="collapseSolution7" class="accordion-collapse collapse" aria-labelledby="headingSolution7" data-bs-parent="#accordionSolution7">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a>acronym <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a>    acronym <span class="op">=</span> acronym <span class="op">+</span> word[<span class="dv">0</span>].upper()</span>
-<span id="cb25-4"><a href="#cb25-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(acronym)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a>acronym <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a><span class="cf">for</span> word <span class="kw">in</span> [<span class="st">"red"</span>, <span class="st">"green"</span>, <span class="st">"blue"</span>]:</span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a>    acronym <span class="op">=</span> acronym <span class="op">+</span> word[<span class="dv">0</span>].upper()</span>
+<span id="cb25-4"><a href="#cb25-4" tabindex="-1"></a><span class="bu">print</span>(acronym)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7151,13 +7152,13 @@ <h3 class="callout-title">Cumulative Sum<a class="anchor" aria-label="anchor" hr
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>cumulative.append(total)</span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
-<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> total <span class="op">+</span> number</span>
-<span id="cb26-5"><a href="#cb26-5" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb26-6"><a href="#cb26-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span>
-<span id="cb26-7"><a href="#cb26-7" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>cumulative.append(total)</span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
+<span id="cb26-4"><a href="#cb26-4" tabindex="-1"></a>total <span class="op">=</span> total <span class="op">+</span> number</span>
+<span id="cb26-5"><a href="#cb26-5" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb26-6"><a href="#cb26-6" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span>
+<span id="cb26-7"><a href="#cb26-7" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -7167,18 +7168,18 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution8" aria-expanded="false" aria-controls="collapseSolution8">
   <h4 class="accordion-header" id="headingSolution8">Show me the solution</h4>
 </button>
-<div id="collapseSolution8" class="accordion-collapse collapse" data-bs-parent="#accordionSolution8" aria-labelledby="headingSolution8">
+<div id="collapseSolution8" class="accordion-collapse collapse" aria-labelledby="headingSolution8" data-bs-parent="#accordionSolution8">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span>
-<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
-<span id="cb27-4"><a href="#cb27-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
-<span id="cb27-5"><a href="#cb27-5" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> number</span>
-<span id="cb27-6"><a href="#cb27-6" aria-hidden="true" tabindex="-1"></a>    cumulative.append(total)</span>
-<span id="cb27-7"><a href="#cb27-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>total <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>data <span class="op">=</span> [<span class="dv">1</span>,<span class="dv">2</span>,<span class="dv">2</span>,<span class="dv">5</span>]</span>
+<span id="cb27-3"><a href="#cb27-3" tabindex="-1"></a>cumulative <span class="op">=</span> []</span>
+<span id="cb27-4"><a href="#cb27-4" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> data:</span>
+<span id="cb27-5"><a href="#cb27-5" tabindex="-1"></a>    total <span class="op">=</span> total <span class="op">+</span> number</span>
+<span id="cb27-6"><a href="#cb27-6" tabindex="-1"></a>    cumulative.append(total)</span>
+<span id="cb27-7"><a href="#cb27-7" tabindex="-1"></a><span class="bu">print</span>(cumulative)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7205,13 +7206,13 @@ <h3 class="callout-title">Identifying Variable Name Errors<a class="anchor" aria
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
-<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> (Number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb28-4"><a href="#cb28-4" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> a</span>
-<span id="cb28-5"><a href="#cb28-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb28-6"><a href="#cb28-6" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
-<span id="cb28-7"><a href="#cb28-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
+<span id="cb28-3"><a href="#cb28-3" tabindex="-1"></a>    <span class="cf">if</span> (Number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb28-4"><a href="#cb28-4" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> a</span>
+<span id="cb28-5"><a href="#cb28-5" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb28-6"><a href="#cb28-6" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
+<span id="cb28-7"><a href="#cb28-7" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7221,7 +7222,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution9" aria-expanded="false" aria-controls="collapseSolution9">
   <h4 class="accordion-header" id="headingSolution9">Show me the solution</h4>
 </button>
-<div id="collapseSolution9" class="accordion-collapse collapse" data-bs-parent="#accordionSolution9" aria-labelledby="headingSolution9">
+<div id="collapseSolution9" class="accordion-collapse collapse" aria-labelledby="headingSolution9" data-bs-parent="#accordionSolution9">
 <div class="accordion-body">
 <ul>
 <li>Python variable names are case sensitive: <code>number</code> and
@@ -7234,14 +7235,14 @@ <h4 class="accordion-header" id="headingSolution9">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb29">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a>message <span class="op">=</span> <span class="st">""</span></span>
-<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
-<span id="cb29-4"><a href="#cb29-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> (number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb29-5"><a href="#cb29-5" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"a"</span></span>
-<span id="cb29-6"><a href="#cb29-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb29-7"><a href="#cb29-7" aria-hidden="true" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
-<span id="cb29-8"><a href="#cb29-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" tabindex="-1"></a>message <span class="op">=</span> <span class="st">""</span></span>
+<span id="cb29-2"><a href="#cb29-2" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb29-3"><a href="#cb29-3" tabindex="-1"></a>    <span class="co"># use a if the number is a multiple of 3, otherwise use b</span></span>
+<span id="cb29-4"><a href="#cb29-4" tabindex="-1"></a>    <span class="cf">if</span> (number <span class="op">%</span> <span class="dv">3</span>) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb29-5"><a href="#cb29-5" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"a"</span></span>
+<span id="cb29-6"><a href="#cb29-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb29-7"><a href="#cb29-7" tabindex="-1"></a>        message <span class="op">=</span> message <span class="op">+</span> <span class="st">"b"</span></span>
+<span id="cb29-8"><a href="#cb29-8" tabindex="-1"></a><span class="bu">print</span>(message)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7265,8 +7266,8 @@ <h3 class="callout-title">Identifying Item Errors<a class="anchor" aria-label="a
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
-<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">4</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
+<span id="cb30-2"><a href="#cb30-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">4</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -7276,15 +7277,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution10" aria-expanded="false" aria-controls="collapseSolution10">
   <h4 class="accordion-header" id="headingSolution10">Show me the solution</h4>
 </button>
-<div id="collapseSolution10" class="accordion-collapse collapse" data-bs-parent="#accordionSolution10" aria-labelledby="headingSolution10">
+<div id="collapseSolution10" class="accordion-collapse collapse" aria-labelledby="headingSolution10" data-bs-parent="#accordionSolution10">
 <div class="accordion-body">
 <p>This list has 4 elements and the index to access the last element in
 the list is <code>3</code>.</p>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
-<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">3</span>])</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>seasons <span class="op">=</span> [<span class="st">'Spring'</span>, <span class="st">'Summer'</span>, <span class="st">'Fall'</span>, <span class="st">'Winter'</span>]</span>
+<span id="cb31-2"><a href="#cb31-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'My favorite season is '</span>, seasons[<span class="dv">3</span>])</span></code></pre>
 </div>
 </div>
 </div>
@@ -7371,13 +7372,13 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">3.54</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(mass, <span class="st">'is large'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">2.07</span></span>
-<span id="cb1-6"><a href="#cb1-6" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb1-7"><a href="#cb1-7" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span> (mass, <span class="st">'is large'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">3.54</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    <span class="bu">print</span>(mass, <span class="st">'is large'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a></span>
+<span id="cb1-5"><a href="#cb1-5" tabindex="-1"></a>mass <span class="op">=</span> <span class="fl">2.07</span></span>
+<span id="cb1-6"><a href="#cb1-6" tabindex="-1"></a><span class="cf">if</span> mass <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb1-7"><a href="#cb1-7" tabindex="-1"></a>    <span class="bu">print</span> (mass, <span class="st">'is large'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7395,10 +7396,10 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
-<span id="cb3-3"><a href="#cb3-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb3-4"><a href="#cb3-4" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
+<span id="cb3-3"><a href="#cb3-3" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb3-4"><a href="#cb3-4" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7419,12 +7420,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb5-6"><a href="#cb5-6" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7450,14 +7451,14 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">9.0</span>:</span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is HUGE'</span>)</span>
-<span id="cb7-5"><a href="#cb7-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
-<span id="cb7-6"><a href="#cb7-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
-<span id="cb7-7"><a href="#cb7-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb7-8"><a href="#cb7-8" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a>masses <span class="op">=</span> [<span class="fl">3.54</span>, <span class="fl">2.07</span>, <span class="fl">9.22</span>, <span class="fl">1.86</span>, <span class="fl">1.71</span>]</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> masses:</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="fl">9.0</span>:</span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is HUGE'</span>)</span>
+<span id="cb7-5"><a href="#cb7-5" tabindex="-1"></a>    <span class="cf">elif</span> m <span class="op">&gt;</span> <span class="fl">3.0</span>:</span>
+<span id="cb7-6"><a href="#cb7-6" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
+<span id="cb7-7"><a href="#cb7-7" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb7-8"><a href="#cb7-8" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7479,13 +7480,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>grade <span class="op">=</span> <span class="dv">85</span></span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> grade <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is A'</span>)</span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">80</span>:</span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is B'</span>)</span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is C'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>grade <span class="op">=</span> <span class="dv">85</span></span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="cf">if</span> grade <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is A'</span>)</span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">80</span>:</span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is B'</span>)</span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a><span class="cf">elif</span> grade <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'grade is C'</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7499,12 +7500,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
-<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a><span class="cf">else</span>:</span>
-<span id="cb11-5"><a href="#cb11-5" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'adjusting velocity'</span>)</span>
-<span id="cb11-6"><a href="#cb11-6" aria-hidden="true" tabindex="-1"></a>    velocity <span class="op">=</span> <span class="fl">50.0</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
+<span id="cb11-4"><a href="#cb11-4" tabindex="-1"></a><span class="cf">else</span>:</span>
+<span id="cb11-5"><a href="#cb11-5" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'adjusting velocity'</span>)</span>
+<span id="cb11-6"><a href="#cb11-6" tabindex="-1"></a>    velocity <span class="op">=</span> <span class="fl">50.0</span></span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7518,16 +7519,16 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>): <span class="co"># execute the loop 5 times</span></span>
-<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(i, <span class="st">':'</span>, velocity)</span>
-<span id="cb13-4"><a href="#cb13-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
-<span id="cb13-5"><a href="#cb13-5" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
-<span id="cb13-6"><a href="#cb13-6" aria-hidden="true" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">-</span> <span class="fl">5.0</span></span>
-<span id="cb13-7"><a href="#cb13-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb13-8"><a href="#cb13-8" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too slow'</span>)</span>
-<span id="cb13-9"><a href="#cb13-9" aria-hidden="true" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">+</span> <span class="fl">10.0</span></span>
-<span id="cb13-10"><a href="#cb13-10" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'final velocity:'</span>, velocity)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>velocity <span class="op">=</span> <span class="fl">10.0</span></span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>): <span class="co"># execute the loop 5 times</span></span>
+<span id="cb13-3"><a href="#cb13-3" tabindex="-1"></a>    <span class="bu">print</span>(i, <span class="st">':'</span>, velocity)</span>
+<span id="cb13-4"><a href="#cb13-4" tabindex="-1"></a>    <span class="cf">if</span> velocity <span class="op">&gt;</span> <span class="fl">20.0</span>:</span>
+<span id="cb13-5"><a href="#cb13-5" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too fast'</span>)</span>
+<span id="cb13-6"><a href="#cb13-6" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">-</span> <span class="fl">5.0</span></span>
+<span id="cb13-7"><a href="#cb13-7" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb13-8"><a href="#cb13-8" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">'moving too slow'</span>)</span>
+<span id="cb13-9"><a href="#cb13-9" tabindex="-1"></a>        velocity <span class="op">=</span> velocity <span class="op">+</span> <span class="fl">10.0</span></span>
+<span id="cb13-10"><a href="#cb13-10" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'final velocity:'</span>, velocity)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7626,12 +7627,13 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <code>velocity</code>, since its value is updated by the last iteration
 of the loop.</li>
 </ul>
-<div id="compound-relations-using-and-or-and-parentheses" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="compound-relations-using-and-or-and-parentheses" class="callout-inner">
-<h3 class="callout-title">Compound Relations Using<code>and</code>,<code>or</code>, and Parentheses<a class="anchor" aria-label="anchor" href="#compound-relations-using-and-or-and-parentheses"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="compound-relations-using-and-or-and-parentheses">Compound Relations Using <code>and</code>,
+<code>or</code>, and Parentheses<a class="anchor" aria-label="anchor" href="#compound-relations-using-and-or-and-parentheses"></a>
 </h3>
 <div class="callout-content">
 <p>Often, you want some combination of things to be true. You can
@@ -7640,19 +7642,19 @@ <h3 class="callout-title">Compound Relations Using<code>and</code>,<code>or</cod
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a>mass     <span class="op">=</span> [ <span class="fl">3.54</span>,  <span class="fl">2.07</span>,  <span class="fl">9.22</span>,  <span class="fl">1.86</span>,  <span class="fl">1.71</span>]</span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>velocity <span class="op">=</span> [<span class="fl">10.00</span>, <span class="fl">20.00</span>, <span class="fl">30.00</span>, <span class="fl">25.00</span>, <span class="fl">20.00</span>]</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb15-5"><a href="#cb15-5" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>):</span>
-<span id="cb15-6"><a href="#cb15-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> mass[i] <span class="op">&gt;</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
-<span id="cb15-7"><a href="#cb15-7" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Fast heavy object.  Duck!"</span>)</span>
-<span id="cb15-8"><a href="#cb15-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&gt;</span> <span class="dv">2</span> <span class="kw">and</span> mass[i] <span class="op">&lt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
-<span id="cb15-9"><a href="#cb15-9" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Normal traffic"</span>)</span>
-<span id="cb15-10"><a href="#cb15-10" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
-<span id="cb15-11"><a href="#cb15-11" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Slow light object.  Ignore it"</span>)</span>
-<span id="cb15-12"><a href="#cb15-12" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb15-13"><a href="#cb15-13" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Whoa!  Something is up with the data.  Check it"</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a>mass     <span class="op">=</span> [ <span class="fl">3.54</span>,  <span class="fl">2.07</span>,  <span class="fl">9.22</span>,  <span class="fl">1.86</span>,  <span class="fl">1.71</span>]</span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>velocity <span class="op">=</span> [<span class="fl">10.00</span>, <span class="fl">20.00</span>, <span class="fl">30.00</span>, <span class="fl">25.00</span>, <span class="fl">20.00</span>]</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a></span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb15-5"><a href="#cb15-5" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">5</span>):</span>
+<span id="cb15-6"><a href="#cb15-6" tabindex="-1"></a>    <span class="cf">if</span> mass[i] <span class="op">&gt;</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
+<span id="cb15-7"><a href="#cb15-7" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Fast heavy object.  Duck!"</span>)</span>
+<span id="cb15-8"><a href="#cb15-8" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&gt;</span> <span class="dv">2</span> <span class="kw">and</span> mass[i] <span class="op">&lt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
+<span id="cb15-9"><a href="#cb15-9" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Normal traffic"</span>)</span>
+<span id="cb15-10"><a href="#cb15-10" tabindex="-1"></a>    <span class="cf">elif</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">and</span> velocity[i] <span class="op">&lt;=</span> <span class="dv">20</span>:</span>
+<span id="cb15-11"><a href="#cb15-11" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Slow light object.  Ignore it"</span>)</span>
+<span id="cb15-12"><a href="#cb15-12" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb15-13"><a href="#cb15-13" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"Whoa!  Something is up with the data.  Check it"</span>)</span></code></pre>
 </div>
 <p>Just like with arithmetic, you can and should use parentheses
 whenever there is possible ambiguity. A good general rule is to
@@ -7661,14 +7663,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span></code></pre>
 </div>
 <p>write one of these:</p>
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> (mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span>) <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> (mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>):</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="cf">if</span> (mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> mass[i] <span class="op">&gt;=</span> <span class="dv">5</span>) <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>:</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a><span class="cf">if</span> mass[i] <span class="op">&lt;=</span> <span class="dv">2</span> <span class="kw">or</span> (mass[i] <span class="op">&gt;=</span> <span class="dv">5</span> <span class="kw">and</span> velocity[i] <span class="op">&gt;</span> <span class="dv">20</span>):</span></code></pre>
 </div>
 <p>so it is perfectly clear to a reader (and to Python) what you really
 mean.</p>
@@ -7687,12 +7689,12 @@ <h3 class="callout-title">Tracing Execution<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb18">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">71.9</span></span>
-<span id="cb18-2"><a href="#cb18-2" aria-hidden="true" tabindex="-1"></a><span class="cf">if</span> pressure <span class="op">&gt;</span> <span class="fl">50.0</span>:</span>
-<span id="cb18-3"><a href="#cb18-3" aria-hidden="true" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">25.0</span></span>
-<span id="cb18-4"><a href="#cb18-4" aria-hidden="true" tabindex="-1"></a><span class="cf">elif</span> pressure <span class="op">&lt;=</span> <span class="fl">50.0</span>:</span>
-<span id="cb18-5"><a href="#cb18-5" aria-hidden="true" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">0.0</span></span>
-<span id="cb18-6"><a href="#cb18-6" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(pressure)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">71.9</span></span>
+<span id="cb18-2"><a href="#cb18-2" tabindex="-1"></a><span class="cf">if</span> pressure <span class="op">&gt;</span> <span class="fl">50.0</span>:</span>
+<span id="cb18-3"><a href="#cb18-3" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">25.0</span></span>
+<span id="cb18-4"><a href="#cb18-4" tabindex="-1"></a><span class="cf">elif</span> pressure <span class="op">&lt;=</span> <span class="fl">50.0</span>:</span>
+<span id="cb18-5"><a href="#cb18-5" tabindex="-1"></a>    pressure <span class="op">=</span> <span class="fl">0.0</span></span>
+<span id="cb18-6"><a href="#cb18-6" tabindex="-1"></a><span class="bu">print</span>(pressure)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7727,14 +7729,14 @@ <h3 class="callout-title">Trimming Values<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb20">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
-<span id="cb20-2"><a href="#cb20-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> ____</span>
-<span id="cb20-3"><a href="#cb20-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
-<span id="cb20-4"><a href="#cb20-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
-<span id="cb20-5"><a href="#cb20-5" aria-hidden="true" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
-<span id="cb20-6"><a href="#cb20-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb20-7"><a href="#cb20-7" aria-hidden="true" tabindex="-1"></a>        ____</span>
-<span id="cb20-8"><a href="#cb20-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
+<span id="cb20-2"><a href="#cb20-2" tabindex="-1"></a>result <span class="op">=</span> ____</span>
+<span id="cb20-3"><a href="#cb20-3" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
+<span id="cb20-4"><a href="#cb20-4" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
+<span id="cb20-5"><a href="#cb20-5" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
+<span id="cb20-6"><a href="#cb20-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb20-7"><a href="#cb20-7" tabindex="-1"></a>        ____</span>
+<span id="cb20-8"><a href="#cb20-8" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -7754,14 +7756,14 @@ <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> []</span>
-<span id="cb22-3"><a href="#cb22-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
-<span id="cb22-4"><a href="#cb22-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> value <span class="op">&lt;</span> <span class="fl">0.0</span>:</span>
-<span id="cb22-5"><a href="#cb22-5" aria-hidden="true" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
-<span id="cb22-6"><a href="#cb22-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb22-7"><a href="#cb22-7" aria-hidden="true" tabindex="-1"></a>        result.append(<span class="dv">1</span>)</span>
-<span id="cb22-8"><a href="#cb22-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>original <span class="op">=</span> [<span class="op">-</span><span class="fl">1.5</span>, <span class="fl">0.2</span>, <span class="fl">0.4</span>, <span class="fl">0.0</span>, <span class="op">-</span><span class="fl">1.3</span>, <span class="fl">0.4</span>]</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a>result <span class="op">=</span> []</span>
+<span id="cb22-3"><a href="#cb22-3" tabindex="-1"></a><span class="cf">for</span> value <span class="kw">in</span> original:</span>
+<span id="cb22-4"><a href="#cb22-4" tabindex="-1"></a>    <span class="cf">if</span> value <span class="op">&lt;</span> <span class="fl">0.0</span>:</span>
+<span id="cb22-5"><a href="#cb22-5" tabindex="-1"></a>        result.append(<span class="dv">0</span>)</span>
+<span id="cb22-6"><a href="#cb22-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb22-7"><a href="#cb22-7" tabindex="-1"></a>        result.append(<span class="dv">1</span>)</span>
+<span id="cb22-8"><a href="#cb22-8" tabindex="-1"></a><span class="bu">print</span>(result)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7780,12 +7782,12 @@ <h3 class="callout-title">Processing Small Files<a class="anchor" aria-label="an
 <div class="codewrapper sourceCode" id="cb23">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb23-4"><a href="#cb23-4" aria-hidden="true" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb23-5"><a href="#cb23-5" aria-hidden="true" tabindex="-1"></a>    ____:</span>
-<span id="cb23-6"><a href="#cb23-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb23-2"><a href="#cb23-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb23-3"><a href="#cb23-3" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb23-4"><a href="#cb23-4" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb23-5"><a href="#cb23-5" tabindex="-1"></a>    ____:</span>
+<span id="cb23-6"><a href="#cb23-6" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
 </div>
 </div>
 </div>
@@ -7800,12 +7802,12 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb24-4"><a href="#cb24-4" aria-hidden="true" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb24-5"><a href="#cb24-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(contents) <span class="op">&lt;</span> <span class="dv">50</span>:</span>
-<span id="cb24-6"><a href="#cb24-6" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb24-3"><a href="#cb24-3" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb24-4"><a href="#cb24-4" tabindex="-1"></a>    contents <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb24-5"><a href="#cb24-5" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(contents) <span class="op">&lt;</span> <span class="dv">50</span>:</span>
+<span id="cb24-6"><a href="#cb24-6" tabindex="-1"></a>        <span class="bu">print</span>(filename, <span class="bu">len</span>(contents))</span></code></pre>
 </div>
 </div>
 </div>
@@ -7824,15 +7826,15 @@ <h3 class="callout-title">Initializing<a class="anchor" aria-label="anchor" href
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [...some test data...]</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb25-4"><a href="#cb25-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
-<span id="cb25-5"><a href="#cb25-5" aria-hidden="true" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
-<span id="cb25-6"><a href="#cb25-6" aria-hidden="true" tabindex="-1"></a>    ____:</span>
-<span id="cb25-7"><a href="#cb25-7" aria-hidden="true" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(____, v)</span>
-<span id="cb25-8"><a href="#cb25-8" aria-hidden="true" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(____, v)</span>
-<span id="cb25-9"><a href="#cb25-9" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a>values <span class="op">=</span> [...some test data...]</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb25-4"><a href="#cb25-4" tabindex="-1"></a>    <span class="cf">if</span> ____:</span>
+<span id="cb25-5"><a href="#cb25-5" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
+<span id="cb25-6"><a href="#cb25-6" tabindex="-1"></a>    ____:</span>
+<span id="cb25-7"><a href="#cb25-7" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(____, v)</span>
+<span id="cb25-8"><a href="#cb25-8" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(____, v)</span>
+<span id="cb25-9"><a href="#cb25-9" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 <p>What are the advantages and disadvantages of using this method to
 find the range of the data?</p>
@@ -7849,15 +7851,15 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">and</span> largest <span class="kw">is</span> <span class="va">None</span>:</span>
-<span id="cb26-5"><a href="#cb26-5" aria-hidden="true" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
-<span id="cb26-6"><a href="#cb26-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb26-7"><a href="#cb26-7" aria-hidden="true" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(smallest, v)</span>
-<span id="cb26-8"><a href="#cb26-8" aria-hidden="true" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(largest, v)</span>
-<span id="cb26-9"><a href="#cb26-9" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb26-4"><a href="#cb26-4" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">and</span> largest <span class="kw">is</span> <span class="va">None</span>:</span>
+<span id="cb26-5"><a href="#cb26-5" tabindex="-1"></a>        smallest, largest <span class="op">=</span> v, v</span>
+<span id="cb26-6"><a href="#cb26-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb26-7"><a href="#cb26-7" tabindex="-1"></a>        smallest <span class="op">=</span> <span class="bu">min</span>(smallest, v)</span>
+<span id="cb26-8"><a href="#cb26-8" tabindex="-1"></a>        largest <span class="op">=</span> <span class="bu">max</span>(largest, v)</span>
+<span id="cb26-9"><a href="#cb26-9" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 <p>If you wrote <code>== None</code> instead of <code>is None</code>,
 that works too, but Python programmers always write <code>is None</code>
@@ -7871,14 +7873,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
-<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb27-4"><a href="#cb27-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&lt;</span> smallest:</span>
-<span id="cb27-5"><a href="#cb27-5" aria-hidden="true" tabindex="-1"></a>        smallest <span class="op">=</span> v</span>
-<span id="cb27-6"><a href="#cb27-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> largest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&gt;</span> largest:</span>
-<span id="cb27-7"><a href="#cb27-7" aria-hidden="true" tabindex="-1"></a>        largest <span class="op">=</span> v</span>
-<span id="cb27-8"><a href="#cb27-8" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>smallest, largest <span class="op">=</span> <span class="va">None</span>, <span class="va">None</span></span>
+<span id="cb27-3"><a href="#cb27-3" tabindex="-1"></a><span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb27-4"><a href="#cb27-4" tabindex="-1"></a>    <span class="cf">if</span> smallest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&lt;</span> smallest:</span>
+<span id="cb27-5"><a href="#cb27-5" tabindex="-1"></a>        smallest <span class="op">=</span> v</span>
+<span id="cb27-6"><a href="#cb27-6" tabindex="-1"></a>    <span class="cf">if</span> largest <span class="kw">is</span> <span class="va">None</span> <span class="kw">or</span> v <span class="op">&gt;</span> largest:</span>
+<span id="cb27-7"><a href="#cb27-7" tabindex="-1"></a>        largest <span class="op">=</span> v</span>
+<span id="cb27-8"><a href="#cb27-8" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 <p>Now we have one loop, but four comparison tests. There are two ways
 we could improve it further: either use fewer comparisons in each
@@ -7887,10 +7889,10 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a>smallest <span class="op">=</span> <span class="bu">min</span>(values)</span>
-<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a>largest <span class="op">=</span> <span class="bu">max</span>(values)</span>
-<span id="cb28-4"><a href="#cb28-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>values <span class="op">=</span> [<span class="op">-</span><span class="dv">2</span>,<span class="dv">1</span>,<span class="dv">65</span>,<span class="dv">78</span>,<span class="op">-</span><span class="dv">54</span>,<span class="op">-</span><span class="dv">24</span>,<span class="dv">100</span>]</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a>smallest <span class="op">=</span> <span class="bu">min</span>(values)</span>
+<span id="cb28-3"><a href="#cb28-3" tabindex="-1"></a>largest <span class="op">=</span> <span class="bu">max</span>(values)</span>
+<span id="cb28-4"><a href="#cb28-4" tabindex="-1"></a><span class="bu">print</span>(smallest, largest)</span></code></pre>
 </div>
 </div>
 </div>
@@ -7967,10 +7969,10 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> [<span class="st">'data/gapminder_gdp_africa.csv'</span>, <span class="st">'data/gapminder_gdp_asia.csv'</span>]:</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(filename, data.<span class="bu">min</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> [<span class="st">'data/gapminder_gdp_africa.csv'</span>, <span class="st">'data/gapminder_gdp_asia.csv'</span>]:</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename, index_col<span class="op">=</span><span class="st">'country'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    <span class="bu">print</span>(filename, data.<span class="bu">min</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8021,8 +8023,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all csv files in data directory:'</span>, glob.glob(<span class="st">'data/*.csv'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all csv files in data directory:'</span>, glob.glob(<span class="st">'data/*.csv'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8034,7 +8036,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all PDB files:'</span>, glob.glob(<span class="st">'*.pdb'</span>))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'all PDB files:'</span>, glob.glob(<span class="st">'*.pdb'</span>))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8052,9 +8054,9 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_*.csv'</span>):</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(filename, data[<span class="st">'gdpPercap_1952'</span>].<span class="bu">min</span>())</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_*.csv'</span>):</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a>    <span class="bu">print</span>(filename, data[<span class="st">'gdpPercap_1952'</span>].<span class="bu">min</span>())</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8096,7 +8098,7 @@ <h3 class="callout-title">Determining Matches<a class="anchor" aria-label="ancho
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <p>1 is not matched by the glob.</p>
 </div>
@@ -8116,13 +8118,13 @@ <h3 class="callout-title">Minimum File Size<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a>fewest <span class="op">=</span> ____</span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.____(filename)</span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(____, dataframe.shape[<span class="dv">0</span>])</span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a>fewest <span class="op">=</span> ____</span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.____(filename)</span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(____, dataframe.shape[<span class="dv">0</span>])</span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
 </div>
 <p>Note that the <a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.shape.html" class="external-link"><code>DataFrame.shape()</code>
 method</a> returns a tuple with the number of rows and columns of the
@@ -8135,18 +8137,18 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb10">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb10-2"><a href="#cb10-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb10-3"><a href="#cb10-3" aria-hidden="true" tabindex="-1"></a>fewest <span class="op">=</span> <span class="bu">float</span>(<span class="st">'Inf'</span>)</span>
-<span id="cb10-4"><a href="#cb10-4" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
-<span id="cb10-5"><a href="#cb10-5" aria-hidden="true" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb10-6"><a href="#cb10-6" aria-hidden="true" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(fewest, dataframe.shape[<span class="dv">0</span>])</span>
-<span id="cb10-7"><a href="#cb10-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb10-2"><a href="#cb10-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb10-3"><a href="#cb10-3" tabindex="-1"></a>fewest <span class="op">=</span> <span class="bu">float</span>(<span class="st">'Inf'</span>)</span>
+<span id="cb10-4"><a href="#cb10-4" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/*.csv'</span>):</span>
+<span id="cb10-5"><a href="#cb10-5" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb10-6"><a href="#cb10-6" tabindex="-1"></a>    fewest <span class="op">=</span> <span class="bu">min</span>(fewest, dataframe.shape[<span class="dv">0</span>])</span>
+<span id="cb10-7"><a href="#cb10-7" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'smallest file has'</span>, fewest, <span class="st">'records'</span>)</span></code></pre>
 </div>
 <p>You might have chosen to initialize the <code>fewest</code> variable
 with a number greater than the numbers you’re dealing with, but that
@@ -8176,7 +8178,7 @@ <h3 class="callout-title">Comparing Data<a class="anchor" aria-label="anchor" hr
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution3" aria-expanded="false" aria-controls="collapseSolution3">
   <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 </button>
-<div id="collapseSolution3" class="accordion-collapse collapse" data-bs-parent="#accordionSolution3" aria-labelledby="headingSolution3">
+<div id="collapseSolution3" class="accordion-collapse collapse" aria-labelledby="headingSolution3" data-bs-parent="#accordionSolution3">
 <div class="accordion-body">
 <p>This solution builds a useful legend by using the <a href="https://docs.python.org/3/library/stdtypes.html#str.split" class="external-link">string
 <code>split</code> method</a> to extract the <code>region</code> from
@@ -8184,31 +8186,31 @@ <h4 class="accordion-header" id="headingSolution3">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> glob</span>
-<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span>
-<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a>fig, ax <span class="op">=</span> plt.subplots(<span class="dv">1</span>,<span class="dv">1</span>)</span>
-<span id="cb11-5"><a href="#cb11-5" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_gdp*.csv'</span>):</span>
-<span id="cb11-6"><a href="#cb11-6" aria-hidden="true" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb11-7"><a href="#cb11-7" aria-hidden="true" tabindex="-1"></a>    <span class="co"># extract &lt;region&gt; from the filename, expected to be in the format 'data/gapminder_gdp_&lt;region&gt;.csv'.</span></span>
-<span id="cb11-8"><a href="#cb11-8" aria-hidden="true" tabindex="-1"></a>    <span class="co"># we will split the string using the split method and `_` as our separator,</span></span>
-<span id="cb11-9"><a href="#cb11-9" aria-hidden="true" tabindex="-1"></a>    <span class="co"># retrieve the last string in the list that split returns (`&lt;region&gt;.csv`), </span></span>
-<span id="cb11-10"><a href="#cb11-10" aria-hidden="true" tabindex="-1"></a>    <span class="co"># and then remove the `.csv` extension from that string.</span></span>
-<span id="cb11-11"><a href="#cb11-11" aria-hidden="true" tabindex="-1"></a>    region <span class="op">=</span> filename.split(<span class="st">'_'</span>)[<span class="op">-</span><span class="dv">1</span>][:<span class="op">-</span><span class="dv">4</span>] </span>
-<span id="cb11-12"><a href="#cb11-12" aria-hidden="true" tabindex="-1"></a>    dataframe.mean().plot(ax<span class="op">=</span>ax, label<span class="op">=</span>region)</span>
-<span id="cb11-13"><a href="#cb11-13" aria-hidden="true" tabindex="-1"></a>plt.legend()</span>
-<span id="cb11-14"><a href="#cb11-14" aria-hidden="true" tabindex="-1"></a>plt.show()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="im">import</span> glob</span>
+<span id="cb11-2"><a href="#cb11-2" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb11-3"><a href="#cb11-3" tabindex="-1"></a><span class="im">import</span> matplotlib.pyplot <span class="im">as</span> plt</span>
+<span id="cb11-4"><a href="#cb11-4" tabindex="-1"></a>fig, ax <span class="op">=</span> plt.subplots(<span class="dv">1</span>,<span class="dv">1</span>)</span>
+<span id="cb11-5"><a href="#cb11-5" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="st">'data/gapminder_gdp*.csv'</span>):</span>
+<span id="cb11-6"><a href="#cb11-6" tabindex="-1"></a>    dataframe <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb11-7"><a href="#cb11-7" tabindex="-1"></a>    <span class="co"># extract &lt;region&gt; from the filename, expected to be in the format 'data/gapminder_gdp_&lt;region&gt;.csv'.</span></span>
+<span id="cb11-8"><a href="#cb11-8" tabindex="-1"></a>    <span class="co"># we will split the string using the split method and `_` as our separator,</span></span>
+<span id="cb11-9"><a href="#cb11-9" tabindex="-1"></a>    <span class="co"># retrieve the last string in the list that split returns (`&lt;region&gt;.csv`), </span></span>
+<span id="cb11-10"><a href="#cb11-10" tabindex="-1"></a>    <span class="co"># and then remove the `.csv` extension from that string.</span></span>
+<span id="cb11-11"><a href="#cb11-11" tabindex="-1"></a>    region <span class="op">=</span> filename.split(<span class="st">'_'</span>)[<span class="op">-</span><span class="dv">1</span>][:<span class="op">-</span><span class="dv">4</span>] </span>
+<span id="cb11-12"><a href="#cb11-12" tabindex="-1"></a>    dataframe.mean().plot(ax<span class="op">=</span>ax, label<span class="op">=</span>region)</span>
+<span id="cb11-13"><a href="#cb11-13" tabindex="-1"></a>plt.legend()</span>
+<span id="cb11-14"><a href="#cb11-14" tabindex="-1"></a>plt.show()</span></code></pre>
 </div>
 </div>
 </div>
 </div>
 </div>
-<div id="dealing-with-file-paths" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="dealing-with-file-paths" class="callout-inner">
-<h3 class="callout-title">Dealing with File Paths<a class="anchor" aria-label="anchor" href="#dealing-with-file-paths"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="dealing-with-file-paths">Dealing with File Paths<a class="anchor" aria-label="anchor" href="#dealing-with-file-paths"></a>
 </h3>
 <div class="callout-content">
 <p>The <a href="https://docs.python.org/3/library/pathlib.html" class="external-link"><code>pathlib</code>
@@ -8220,10 +8222,10 @@ <h3 class="callout-title">Dealing with File Paths<a class="anchor" aria-label="a
 <div class="codewrapper sourceCode" id="cb12">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="im">from</span> pathlib <span class="im">import</span> Path</span>
-<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a>p <span class="op">=</span> Path(<span class="st">"data/gapminder_gdp_africa.csv"</span>)</span>
-<span id="cb12-4"><a href="#cb12-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(p.parent), <span class="bu">print</span>(p.stem), <span class="bu">print</span>(p.suffix)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" tabindex="-1"></a><span class="im">from</span> pathlib <span class="im">import</span> Path</span>
+<span id="cb12-2"><a href="#cb12-2" tabindex="-1"></a></span>
+<span id="cb12-3"><a href="#cb12-3" tabindex="-1"></a>p <span class="op">=</span> Path(<span class="st">"data/gapminder_gdp_africa.csv"</span>)</span>
+<span id="cb12-4"><a href="#cb12-4" tabindex="-1"></a><span class="bu">print</span>(p.parent), <span class="bu">print</span>(p.stem), <span class="bu">print</span>(p.suffix)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8367,10 +8369,10 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_greeting():</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Hello!'</span>)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'The weather is nice today.'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Right?'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="kw">def</span> print_greeting():</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Hello!'</span>)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'The weather is nice today.'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'Right?'</span>)</span></code></pre>
 </div>
 </section><section id="defining-a-function-does-not-run-it."><h2 class="section-heading">Defining a function does not run it.<a class="anchor" aria-label="anchor" href="#defining-a-function-does-not-run-it."></a>
 </h2>
@@ -8386,7 +8388,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a>print_greeting()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a>print_greeting()</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8414,11 +8416,11 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-5"><a href="#cb4-5" aria-hidden="true" tabindex="-1"></a>print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
+<span id="cb4-3"><a href="#cb4-3" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span>
+<span id="cb4-4"><a href="#cb4-4" tabindex="-1"></a></span>
+<span id="cb4-5"><a href="#cb4-5" tabindex="-1"></a>print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8432,7 +8434,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a>print_date(month<span class="op">=</span><span class="dv">3</span>, day<span class="op">=</span><span class="dv">19</span>, year<span class="op">=</span><span class="dv">1871</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a>print_date(month<span class="op">=</span><span class="dv">3</span>, day<span class="op">=</span><span class="dv">19</span>, year<span class="op">=</span><span class="dv">1871</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8461,16 +8463,16 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
-<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb8-3"><a href="#cb8-3" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
+<span id="cb8-4"><a href="#cb8-4" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span></code></pre>
 </div>
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">=</span> average([<span class="dv">1</span>, <span class="dv">3</span>, <span class="dv">4</span>])</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of actual values:'</span>, a)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a>a <span class="op">=</span> average([<span class="dv">1</span>, <span class="dv">3</span>, <span class="dv">4</span>])</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of actual values:'</span>, a)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8480,7 +8482,7 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb11">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of empty list:'</span>, average([]))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'average of empty list:'</span>, average([]))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8496,8 +8498,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb13">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span>
-<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" tabindex="-1"></a>result <span class="op">=</span> print_date(<span class="dv">1871</span>, <span class="dv">3</span>, <span class="dv">19</span>)</span>
+<span id="cb13-2"><a href="#cb13-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8524,10 +8526,10 @@ <h3 class="callout-title">Identifying Syntax Errors<a class="anchor" aria-label=
 <div class="codewrapper sourceCode" id="cb15">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> another_function</span>
-<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
-<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a>   <span class="bu">print</span>(<span class="st">"But at least python tells us about them!"</span>)</span>
-<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" tabindex="-1"></a><span class="kw">def</span> another_function</span>
+<span id="cb15-2"><a href="#cb15-2" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
+<span id="cb15-3"><a href="#cb15-3" tabindex="-1"></a>   <span class="bu">print</span>(<span class="st">"But at least python tells us about them!"</span>)</span>
+<span id="cb15-4"><a href="#cb15-4" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -8542,10 +8544,10 @@ <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb16">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> another_function():</span>
-<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
-<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"But at least Python tells us about them!"</span>)</span>
-<span id="cb16-4"><a href="#cb16-4" aria-hidden="true" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" tabindex="-1"></a><span class="kw">def</span> another_function():</span>
+<span id="cb16-2"><a href="#cb16-2" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"Syntax errors are annoying."</span>)</span>
+<span id="cb16-3"><a href="#cb16-3" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"But at least Python tells us about them!"</span>)</span>
+<span id="cb16-4"><a href="#cb16-4" tabindex="-1"></a>  <span class="bu">print</span>(<span class="st">"So they are usually not too hard to fix."</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -8563,10 +8565,10 @@ <h3 class="callout-title">Definition and Use<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb17">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> report(pressure):</span>
-<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'pressure is'</span>, pressure)</span>
-<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'calling'</span>, report, <span class="fl">22.5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" tabindex="-1"></a><span class="kw">def</span> report(pressure):</span>
+<span id="cb17-2"><a href="#cb17-2" tabindex="-1"></a>    <span class="bu">print</span>(<span class="st">'pressure is'</span>, pressure)</span>
+<span id="cb17-3"><a href="#cb17-3" tabindex="-1"></a></span>
+<span id="cb17-4"><a href="#cb17-4" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'calling'</span>, report, <span class="fl">22.5</span>)</span></code></pre>
 </div>
 </div>
 </div>
@@ -8590,8 +8592,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb19">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"calling"</span>)</span>
-<span id="cb19-2"><a href="#cb19-2" aria-hidden="true" tabindex="-1"></a>report(<span class="fl">22.5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">"calling"</span>)</span>
+<span id="cb19-2"><a href="#cb19-2" tabindex="-1"></a>report(<span class="fl">22.5</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8617,11 +8619,11 @@ <h3 class="callout-title">Order of Operations<a class="anchor" aria-label="ancho
 <div class="codewrapper sourceCode" id="cb21">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
-<span id="cb21-2"><a href="#cb21-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb21-3"><a href="#cb21-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_time(hour, minute, second):</span>
-<span id="cb21-4"><a href="#cb21-4" aria-hidden="true" tabindex="-1"></a>   time_string <span class="op">=</span> <span class="bu">str</span>(hour) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(minute) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(second)</span>
-<span id="cb21-5"><a href="#cb21-5" aria-hidden="true" tabindex="-1"></a>   <span class="bu">print</span>(time_string)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
+<span id="cb21-2"><a href="#cb21-2" tabindex="-1"></a></span>
+<span id="cb21-3"><a href="#cb21-3" tabindex="-1"></a><span class="kw">def</span> print_time(hour, minute, second):</span>
+<span id="cb21-4"><a href="#cb21-4" tabindex="-1"></a>   time_string <span class="op">=</span> <span class="bu">str</span>(hour) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(minute) <span class="op">+</span> <span class="st">':'</span> <span class="op">+</span> <span class="bu">str</span>(second)</span>
+<span id="cb21-5"><a href="#cb21-5" tabindex="-1"></a>   <span class="bu">print</span>(time_string)</span></code></pre>
 </div>
 <ol start="2" style="list-style-type: decimal">
 <li>After fixing the problem above, explain why running this example
@@ -8630,8 +8632,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb22">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
-<span id="cb22-2"><a href="#cb22-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" tabindex="-1"></a>result <span class="op">=</span> print_time(<span class="dv">11</span>, <span class="dv">37</span>, <span class="dv">59</span>)</span>
+<span id="cb22-2"><a href="#cb22-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'result of call is:'</span>, result)</span></code></pre>
 </div>
 <p>gives this output:</p>
 <div class="codewrapper">
@@ -8686,11 +8688,11 @@ <h3 class="callout-title">Encapsulation<a class="anchor" aria-label="anchor" hre
 <div class="codewrapper sourceCode" id="cb24">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> min_in_data(____):</span>
-<span id="cb24-4"><a href="#cb24-4" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> ____</span>
-<span id="cb24-5"><a href="#cb24-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> ____</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb24-2"><a href="#cb24-2" tabindex="-1"></a></span>
+<span id="cb24-3"><a href="#cb24-3" tabindex="-1"></a><span class="kw">def</span> min_in_data(____):</span>
+<span id="cb24-4"><a href="#cb24-4" tabindex="-1"></a>    data <span class="op">=</span> ____</span>
+<span id="cb24-5"><a href="#cb24-5" tabindex="-1"></a>    <span class="cf">return</span> ____</span></code></pre>
 </div>
 </div>
 </div>
@@ -8705,11 +8707,11 @@ <h4 class="accordion-header" id="headingSolution4">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb25">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb25-3"><a href="#cb25-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> min_in_data(filename):</span>
-<span id="cb25-4"><a href="#cb25-4" aria-hidden="true" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
-<span id="cb25-5"><a href="#cb25-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> data.<span class="bu">min</span>()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb25-2"><a href="#cb25-2" tabindex="-1"></a></span>
+<span id="cb25-3"><a href="#cb25-3" tabindex="-1"></a><span class="kw">def</span> min_in_data(filename):</span>
+<span id="cb25-4"><a href="#cb25-4" tabindex="-1"></a>    data <span class="op">=</span> pd.read_csv(filename)</span>
+<span id="cb25-5"><a href="#cb25-5" tabindex="-1"></a>    <span class="cf">return</span> data.<span class="bu">min</span>()</span></code></pre>
 </div>
 </div>
 </div>
@@ -8730,10 +8732,10 @@ <h3 class="callout-title">Find the First<a class="anchor" aria-label="anchor" hr
 <div class="codewrapper sourceCode" id="cb26">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
-<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> ____:</span>
-<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> ____:</span>
-<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a>            <span class="cf">return</span> ____</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
+<span id="cb26-2"><a href="#cb26-2" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> ____:</span>
+<span id="cb26-3"><a href="#cb26-3" tabindex="-1"></a>        <span class="cf">if</span> ____:</span>
+<span id="cb26-4"><a href="#cb26-4" tabindex="-1"></a>            <span class="cf">return</span> ____</span></code></pre>
 </div>
 </div>
 </div>
@@ -8748,18 +8750,18 @@ <h4 class="accordion-header" id="headingSolution5">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb27">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
-<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> values:</span>
-<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> v <span class="op">&lt;</span> <span class="dv">0</span>:</span>
-<span id="cb27-4"><a href="#cb27-4" aria-hidden="true" tabindex="-1"></a>            <span class="cf">return</span> v</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" tabindex="-1"></a><span class="kw">def</span> first_negative(values):</span>
+<span id="cb27-2"><a href="#cb27-2" tabindex="-1"></a>    <span class="cf">for</span> v <span class="kw">in</span> values:</span>
+<span id="cb27-3"><a href="#cb27-3" tabindex="-1"></a>        <span class="cf">if</span> v <span class="op">&lt;</span> <span class="dv">0</span>:</span>
+<span id="cb27-4"><a href="#cb27-4" tabindex="-1"></a>            <span class="cf">return</span> v</span></code></pre>
 </div>
 <p>If an empty list or a list with all positive values is passed to this
 function, it returns <code>None</code>:</p>
 <div class="codewrapper sourceCode" id="cb28">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a>my_list <span class="op">=</span> []</span>
-<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(first_negative(my_list))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" tabindex="-1"></a>my_list <span class="op">=</span> []</span>
+<span id="cb28-2"><a href="#cb28-2" tabindex="-1"></a><span class="bu">print</span>(first_negative(my_list))</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -8782,16 +8784,16 @@ <h3 class="callout-title">Calling by Name<a class="anchor" aria-label="anchor" h
 <div class="codewrapper sourceCode" id="cb30">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
-<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
-<span id="cb30-3"><a href="#cb30-3" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" tabindex="-1"></a><span class="kw">def</span> print_date(year, month, day):</span>
+<span id="cb30-2"><a href="#cb30-2" tabindex="-1"></a>    joined <span class="op">=</span> <span class="bu">str</span>(year) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(month) <span class="op">+</span> <span class="st">'/'</span> <span class="op">+</span> <span class="bu">str</span>(day)</span>
+<span id="cb30-3"><a href="#cb30-3" tabindex="-1"></a>    <span class="bu">print</span>(joined)</span></code></pre>
 </div>
 <p>We saw that we can call the function using <em>named arguments</em>,
 like this:</p>
 <div class="codewrapper sourceCode" id="cb31">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a>print_date(day<span class="op">=</span><span class="dv">1</span>, month<span class="op">=</span><span class="dv">2</span>, year<span class="op">=</span><span class="dv">2003</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" tabindex="-1"></a>print_date(day<span class="op">=</span><span class="dv">1</span>, month<span class="op">=</span><span class="dv">2</span>, year<span class="op">=</span><span class="dv">2003</span>)</span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>What does <code>print_date(day=1, month=2, year=2003)</code>
@@ -8839,24 +8841,24 @@ <h3 class="callout-title">Encapsulation of an If/Print Block<a class="anchor" ar
 <div class="codewrapper sourceCode" id="cb32">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb32-2"><a href="#cb32-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb32-3"><a href="#cb32-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb32-4"><a href="#cb32-4" aria-hidden="true" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
-<span id="cb32-5"><a href="#cb32-5" aria-hidden="true" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
-<span id="cb32-6"><a href="#cb32-6" aria-hidden="true" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
-<span id="cb32-7"><a href="#cb32-7" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb32-8"><a href="#cb32-8" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(mass)</span>
-<span id="cb32-9"><a href="#cb32-9" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb32-10"><a href="#cb32-10" aria-hidden="true" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
-<span id="cb32-11"><a href="#cb32-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
-<span id="cb32-12"><a href="#cb32-12" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"jumbo"</span>)</span>
-<span id="cb32-13"><a href="#cb32-13" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
-<span id="cb32-14"><a href="#cb32-14" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"large"</span>)</span>
-<span id="cb32-15"><a href="#cb32-15" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
-<span id="cb32-16"><a href="#cb32-16" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"medium"</span>)</span>
-<span id="cb32-17"><a href="#cb32-17" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb32-18"><a href="#cb32-18" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"small"</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb32-2"><a href="#cb32-2" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb32-3"><a href="#cb32-3" tabindex="-1"></a></span>
+<span id="cb32-4"><a href="#cb32-4" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
+<span id="cb32-5"><a href="#cb32-5" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
+<span id="cb32-6"><a href="#cb32-6" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
+<span id="cb32-7"><a href="#cb32-7" tabindex="-1"></a></span>
+<span id="cb32-8"><a href="#cb32-8" tabindex="-1"></a>    <span class="bu">print</span>(mass)</span>
+<span id="cb32-9"><a href="#cb32-9" tabindex="-1"></a></span>
+<span id="cb32-10"><a href="#cb32-10" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
+<span id="cb32-11"><a href="#cb32-11" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
+<span id="cb32-12"><a href="#cb32-12" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"jumbo"</span>)</span>
+<span id="cb32-13"><a href="#cb32-13" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
+<span id="cb32-14"><a href="#cb32-14" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"large"</span>)</span>
+<span id="cb32-15"><a href="#cb32-15" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
+<span id="cb32-16"><a href="#cb32-16" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"medium"</span>)</span>
+<span id="cb32-17"><a href="#cb32-17" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb32-18"><a href="#cb32-18" tabindex="-1"></a>        <span class="bu">print</span>(<span class="st">"small"</span>)</span></code></pre>
 </div>
 <p>The if-block that classifies the eggs might be useful in other
 situations, so to avoid repeating it, we could fold it into a function,
@@ -8865,15 +8867,15 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb33">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a><span class="co"># revised version</span></span>
-<span id="cb33-2"><a href="#cb33-2" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> random</span>
-<span id="cb33-3"><a href="#cb33-3" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
-<span id="cb33-4"><a href="#cb33-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb33-5"><a href="#cb33-5" aria-hidden="true" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
-<span id="cb33-6"><a href="#cb33-6" aria-hidden="true" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
-<span id="cb33-7"><a href="#cb33-7" aria-hidden="true" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
-<span id="cb33-8"><a href="#cb33-8" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb33-9"><a href="#cb33-9" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(mass, get_egg_label(mass))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" tabindex="-1"></a><span class="co"># revised version</span></span>
+<span id="cb33-2"><a href="#cb33-2" tabindex="-1"></a><span class="im">import</span> random</span>
+<span id="cb33-3"><a href="#cb33-3" tabindex="-1"></a><span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">10</span>):</span>
+<span id="cb33-4"><a href="#cb33-4" tabindex="-1"></a></span>
+<span id="cb33-5"><a href="#cb33-5" tabindex="-1"></a>    <span class="co"># simulating the mass of a chicken egg</span></span>
+<span id="cb33-6"><a href="#cb33-6" tabindex="-1"></a>    <span class="co"># the (random) mass will be 70 +/- 20 grams</span></span>
+<span id="cb33-7"><a href="#cb33-7" tabindex="-1"></a>    mass <span class="op">=</span> <span class="dv">70</span> <span class="op">+</span> <span class="fl">20.0</span> <span class="op">*</span> (<span class="fl">2.0</span> <span class="op">*</span> random.random() <span class="op">-</span> <span class="fl">1.0</span>)</span>
+<span id="cb33-8"><a href="#cb33-8" tabindex="-1"></a></span>
+<span id="cb33-9"><a href="#cb33-9" tabindex="-1"></a>    <span class="bu">print</span>(mass, get_egg_label(mass))</span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>Create a function definition for <code>get_egg_label()</code> that
@@ -8900,22 +8902,22 @@ <h4 class="accordion-header" id="headingSolution7">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb34">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> get_egg_label(mass):</span>
-<span id="cb34-2"><a href="#cb34-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
-<span id="cb34-3"><a href="#cb34-3" aria-hidden="true" tabindex="-1"></a>    egg_label <span class="op">=</span> <span class="st">"Unlabelled"</span></span>
-<span id="cb34-4"><a href="#cb34-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
-<span id="cb34-5"><a href="#cb34-5" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"warning: egg might be dirty"</span></span>
-<span id="cb34-6"><a href="#cb34-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
-<span id="cb34-7"><a href="#cb34-7" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"jumbo"</span></span>
-<span id="cb34-8"><a href="#cb34-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
-<span id="cb34-9"><a href="#cb34-9" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"large"</span></span>
-<span id="cb34-10"><a href="#cb34-10" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
-<span id="cb34-11"><a href="#cb34-11" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"medium"</span></span>
-<span id="cb34-12"><a href="#cb34-12" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">50</span>:</span>
-<span id="cb34-13"><a href="#cb34-13" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"too light, probably spoiled"</span></span>
-<span id="cb34-14"><a href="#cb34-14" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb34-15"><a href="#cb34-15" aria-hidden="true" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"small"</span></span>
-<span id="cb34-16"><a href="#cb34-16" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> egg_label</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" tabindex="-1"></a><span class="kw">def</span> get_egg_label(mass):</span>
+<span id="cb34-2"><a href="#cb34-2" tabindex="-1"></a>    <span class="co"># egg sizing machinery prints a label</span></span>
+<span id="cb34-3"><a href="#cb34-3" tabindex="-1"></a>    egg_label <span class="op">=</span> <span class="st">"Unlabelled"</span></span>
+<span id="cb34-4"><a href="#cb34-4" tabindex="-1"></a>    <span class="cf">if</span> mass <span class="op">&gt;=</span> <span class="dv">90</span>:</span>
+<span id="cb34-5"><a href="#cb34-5" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"warning: egg might be dirty"</span></span>
+<span id="cb34-6"><a href="#cb34-6" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">85</span>:</span>
+<span id="cb34-7"><a href="#cb34-7" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"jumbo"</span></span>
+<span id="cb34-8"><a href="#cb34-8" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&gt;=</span> <span class="dv">70</span>:</span>
+<span id="cb34-9"><a href="#cb34-9" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"large"</span></span>
+<span id="cb34-10"><a href="#cb34-10" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">70</span> <span class="kw">and</span> mass <span class="op">&gt;=</span> <span class="dv">55</span>:</span>
+<span id="cb34-11"><a href="#cb34-11" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"medium"</span></span>
+<span id="cb34-12"><a href="#cb34-12" tabindex="-1"></a>    <span class="cf">elif</span> mass <span class="op">&lt;</span> <span class="dv">50</span>:</span>
+<span id="cb34-13"><a href="#cb34-13" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"too light, probably spoiled"</span></span>
+<span id="cb34-14"><a href="#cb34-14" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb34-15"><a href="#cb34-15" tabindex="-1"></a>        egg_label <span class="op">=</span> <span class="st">"small"</span></span>
+<span id="cb34-16"><a href="#cb34-16" tabindex="-1"></a>    <span class="cf">return</span> egg_label</span></code></pre>
 </div>
 </div>
 </div>
@@ -8933,10 +8935,10 @@ <h3 class="callout-title">Encapsulating Data Analysis<a class="anchor" aria-labe
 <div class="codewrapper sourceCode" id="cb35">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
-<span id="cb35-2"><a href="#cb35-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb35-3"><a href="#cb35-3" aria-hidden="true" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb35-4"><a href="#cb35-4" aria-hidden="true" tabindex="-1"></a>japan <span class="op">=</span> data_asia.loc[<span class="st">'Japan'</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" tabindex="-1"></a><span class="im">import</span> pandas <span class="im">as</span> pd</span>
+<span id="cb35-2"><a href="#cb35-2" tabindex="-1"></a></span>
+<span id="cb35-3"><a href="#cb35-3" tabindex="-1"></a>data_asia <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_asia.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb35-4"><a href="#cb35-4" tabindex="-1"></a>japan <span class="op">=</span> data_asia.loc[<span class="st">'Japan'</span>]</span></code></pre>
 </div>
 <ol style="list-style-type: decimal">
 <li>Complete the statements below to obtain the average GDP for Japan
@@ -8945,9 +8947,9 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb36">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" aria-hidden="true" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
-<span id="cb36-2"><a href="#cb36-2" aria-hidden="true" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> ____)</span>
-<span id="cb36-3"><a href="#cb36-3" aria-hidden="true" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> ___] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> ___]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
+<span id="cb36-2"><a href="#cb36-2" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> ____)</span>
+<span id="cb36-3"><a href="#cb36-3" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> ___] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> ___]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
 </div>
 <ol start="2" style="list-style-type: decimal">
 <li>Abstract the code above into a single function.</li>
@@ -8955,12 +8957,12 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb37">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
-<span id="cb37-2"><a href="#cb37-2" aria-hidden="true" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span><span class="op">+</span>___<span class="op">+</span><span class="st">'.csv'</span>,delimiter<span class="op">=</span><span class="st">','</span>,index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb37-3"><a href="#cb37-3" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb37-4"><a href="#cb37-4" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb37-5"><a href="#cb37-5" aria-hidden="true" tabindex="-1"></a>    ____</span>
-<span id="cb37-6"><a href="#cb37-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
+<span id="cb37-2"><a href="#cb37-2" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span><span class="op">+</span>___<span class="op">+</span><span class="st">'.csv'</span>,delimiter<span class="op">=</span><span class="st">','</span>,index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb37-3"><a href="#cb37-3" tabindex="-1"></a>    ____</span>
+<span id="cb37-4"><a href="#cb37-4" tabindex="-1"></a>    ____</span>
+<span id="cb37-5"><a href="#cb37-5" tabindex="-1"></a>    ____</span>
+<span id="cb37-6"><a href="#cb37-6" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
 </div>
 <ol start="3" style="list-style-type: decimal">
 <li>How would you generalize this function if you did not know
@@ -8986,9 +8988,9 @@ <h4 class="accordion-header" id="headingSolution8">Show me the solution</h4>
 <div class="codewrapper sourceCode" id="cb38">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
-<span id="cb38-2"><a href="#cb38-2" aria-hidden="true" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
-<span id="cb38-3"><a href="#cb38-3" aria-hidden="true" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" tabindex="-1"></a>year <span class="op">=</span> <span class="dv">1983</span></span>
+<span id="cb38-2"><a href="#cb38-2" tabindex="-1"></a>gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
+<span id="cb38-3"><a href="#cb38-3" tabindex="-1"></a>avg <span class="op">=</span> (japan.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> japan.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>]) <span class="op">/</span> <span class="dv">2</span></span></code></pre>
 </div>
 <ol start="2" style="list-style-type: decimal">
 <li>That code as a function is:</li>
@@ -8996,12 +8998,12 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb39">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
-<span id="cb39-2"><a href="#cb39-2" aria-hidden="true" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb39-3"><a href="#cb39-3" aria-hidden="true" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
-<span id="cb39-4"><a href="#cb39-4" aria-hidden="true" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
-<span id="cb39-5"><a href="#cb39-5" aria-hidden="true" tabindex="-1"></a>    avg <span class="op">=</span> (c.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> c.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>])<span class="op">/</span><span class="dv">2</span></span>
-<span id="cb39-6"><a href="#cb39-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
+<span id="cb39-2"><a href="#cb39-2" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb39-3"><a href="#cb39-3" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
+<span id="cb39-4"><a href="#cb39-4" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
+<span id="cb39-5"><a href="#cb39-5" tabindex="-1"></a>    avg <span class="op">=</span> (c.loc[gdp_decade <span class="op">+</span> <span class="st">'2'</span>] <span class="op">+</span> c.loc[gdp_decade <span class="op">+</span> <span class="st">'7'</span>])<span class="op">/</span><span class="dv">2</span></span>
+<span id="cb39-6"><a href="#cb39-6" tabindex="-1"></a>    <span class="cf">return</span> avg</span></code></pre>
 </div>
 <ol start="3" style="list-style-type: decimal">
 <li>To obtain the average for the relevant years, we need to loop over
@@ -9010,23 +9012,23 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb40">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
-<span id="cb40-2"><a href="#cb40-2" aria-hidden="true" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
-<span id="cb40-3"><a href="#cb40-3" aria-hidden="true" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
-<span id="cb40-4"><a href="#cb40-4" aria-hidden="true" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
-<span id="cb40-5"><a href="#cb40-5" aria-hidden="true" tabindex="-1"></a>    total <span class="op">=</span> <span class="fl">0.0</span></span>
-<span id="cb40-6"><a href="#cb40-6" aria-hidden="true" tabindex="-1"></a>    num_years <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb40-7"><a href="#cb40-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> yr_header <span class="kw">in</span> c.index: <span class="co"># c's index contains reported years</span></span>
-<span id="cb40-8"><a href="#cb40-8" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> yr_header.startswith(gdp_decade):</span>
-<span id="cb40-9"><a href="#cb40-9" aria-hidden="true" tabindex="-1"></a>            total <span class="op">=</span> total <span class="op">+</span> c.loc[yr_header]</span>
-<span id="cb40-10"><a href="#cb40-10" aria-hidden="true" tabindex="-1"></a>            num_years <span class="op">=</span> num_years <span class="op">+</span> <span class="dv">1</span></span>
-<span id="cb40-11"><a href="#cb40-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> total<span class="op">/</span>num_years</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" tabindex="-1"></a><span class="kw">def</span> avg_gdp_in_decade(country, continent, year):</span>
+<span id="cb40-2"><a href="#cb40-2" tabindex="-1"></a>    data_countries <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_gdp_'</span> <span class="op">+</span> continent <span class="op">+</span> <span class="st">'.csv'</span>, index_col<span class="op">=</span><span class="dv">0</span>)</span>
+<span id="cb40-3"><a href="#cb40-3" tabindex="-1"></a>    c <span class="op">=</span> data_countries.loc[country]</span>
+<span id="cb40-4"><a href="#cb40-4" tabindex="-1"></a>    gdp_decade <span class="op">=</span> <span class="st">'gdpPercap_'</span> <span class="op">+</span> <span class="bu">str</span>(year <span class="op">//</span> <span class="dv">10</span>)</span>
+<span id="cb40-5"><a href="#cb40-5" tabindex="-1"></a>    total <span class="op">=</span> <span class="fl">0.0</span></span>
+<span id="cb40-6"><a href="#cb40-6" tabindex="-1"></a>    num_years <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb40-7"><a href="#cb40-7" tabindex="-1"></a>    <span class="cf">for</span> yr_header <span class="kw">in</span> c.index: <span class="co"># c's index contains reported years</span></span>
+<span id="cb40-8"><a href="#cb40-8" tabindex="-1"></a>        <span class="cf">if</span> yr_header.startswith(gdp_decade):</span>
+<span id="cb40-9"><a href="#cb40-9" tabindex="-1"></a>            total <span class="op">=</span> total <span class="op">+</span> c.loc[yr_header]</span>
+<span id="cb40-10"><a href="#cb40-10" tabindex="-1"></a>            num_years <span class="op">=</span> num_years <span class="op">+</span> <span class="dv">1</span></span>
+<span id="cb40-11"><a href="#cb40-11" tabindex="-1"></a>    <span class="cf">return</span> total<span class="op">/</span>num_years</span></code></pre>
 </div>
 <p>The function can now be called by:</p>
 <div class="codewrapper sourceCode" id="cb41">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" aria-hidden="true" tabindex="-1"></a>avg_gdp_in_decade(<span class="st">'Japan'</span>,<span class="st">'asia'</span>,<span class="dv">1983</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" tabindex="-1"></a>avg_gdp_in_decade(<span class="st">'Japan'</span>,<span class="st">'asia'</span>,<span class="dv">1983</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -9092,18 +9094,18 @@ <h4 class="accordion-header" id="headingSolution9">Show me the solution</h4>
 <li><div class="codewrapper sourceCode" id="cb43">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a>  <span class="kw">def</span> logistic_map(x, r):</span>
-<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a>      <span class="cf">return</span> r <span class="op">*</span> x <span class="op">*</span> (<span class="dv">1</span> <span class="op">-</span> x)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" tabindex="-1"></a>  <span class="kw">def</span> logistic_map(x, r):</span>
+<span id="cb43-2"><a href="#cb43-2" tabindex="-1"></a>      <span class="cf">return</span> r <span class="op">*</span> x <span class="op">*</span> (<span class="dv">1</span> <span class="op">-</span> x)</span></code></pre>
 </div></li>
 <li><div class="codewrapper sourceCode" id="cb44">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" aria-hidden="true" tabindex="-1"></a>  initial_population <span class="op">=</span> <span class="fl">0.5</span></span>
-<span id="cb44-2"><a href="#cb44-2" aria-hidden="true" tabindex="-1"></a>  t_final <span class="op">=</span> <span class="dv">10</span></span>
-<span id="cb44-3"><a href="#cb44-3" aria-hidden="true" tabindex="-1"></a>  r <span class="op">=</span> <span class="fl">1.0</span></span>
-<span id="cb44-4"><a href="#cb44-4" aria-hidden="true" tabindex="-1"></a>  population <span class="op">=</span> [initial_population]</span>
-<span id="cb44-5"><a href="#cb44-5" aria-hidden="true" tabindex="-1"></a>  <span class="cf">for</span> t <span class="kw">in</span> <span class="bu">range</span>(t_final):</span>
-<span id="cb44-6"><a href="#cb44-6" aria-hidden="true" tabindex="-1"></a>      population.append( logistic_map(population[t], r) )</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" tabindex="-1"></a>  initial_population <span class="op">=</span> <span class="fl">0.5</span></span>
+<span id="cb44-2"><a href="#cb44-2" tabindex="-1"></a>  t_final <span class="op">=</span> <span class="dv">10</span></span>
+<span id="cb44-3"><a href="#cb44-3" tabindex="-1"></a>  r <span class="op">=</span> <span class="fl">1.0</span></span>
+<span id="cb44-4"><a href="#cb44-4" tabindex="-1"></a>  population <span class="op">=</span> [initial_population]</span>
+<span id="cb44-5"><a href="#cb44-5" tabindex="-1"></a>  <span class="cf">for</span> t <span class="kw">in</span> <span class="bu">range</span>(t_final):</span>
+<span id="cb44-6"><a href="#cb44-6" tabindex="-1"></a>      population.append( logistic_map(population[t], r) )</span></code></pre>
 </div></li>
 <li>```python def iterate(initial_population, t_final, r): population =
 [initial_population] for t in range(t_final): population.append(
@@ -9123,12 +9125,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 </div>
 </div>
 </div>
-<div id="using-functions-with-conditionals-in-pandas" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="using-functions-with-conditionals-in-pandas" class="callout-inner">
-<h3 class="callout-title">Using Functions With Conditionals in
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="using-functions-with-conditionals-in-pandas">Using Functions With Conditionals in
 Pandas<a class="anchor" aria-label="anchor" href="#using-functions-with-conditionals-in-pandas"></a>
 </h3>
 <div class="callout-content">
@@ -9138,24 +9140,24 @@ <h3 class="callout-title">Using Functions With Conditionals in
 <div class="codewrapper sourceCode" id="cb46">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> calculate_life_quartile(exp):</span>
-<span id="cb46-2"><a href="#cb46-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> exp <span class="op">&lt;</span> <span class="fl">58.41</span>:</span>
-<span id="cb46-3"><a href="#cb46-3" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the first quartile</span></span>
-<span id="cb46-4"><a href="#cb46-4" aria-hidden="true" tabindex="-1"></a>        <span class="cf">return</span> <span class="dv">1</span></span>
-<span id="cb46-5"><a href="#cb46-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">58.41</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">67.05</span>:</span>
-<span id="cb46-6"><a href="#cb46-6" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the second quartile</span></span>
-<span id="cb46-7"><a href="#cb46-7" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">2</span></span>
-<span id="cb46-8"><a href="#cb46-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">67.05</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">71.70</span>:</span>
-<span id="cb46-9"><a href="#cb46-9" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the third quartile</span></span>
-<span id="cb46-10"><a href="#cb46-10" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">3</span></span>
-<span id="cb46-11"><a href="#cb46-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">71.70</span>:</span>
-<span id="cb46-12"><a href="#cb46-12" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation is in the fourth quartile</span></span>
-<span id="cb46-13"><a href="#cb46-13" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">4</span></span>
-<span id="cb46-14"><a href="#cb46-14" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb46-15"><a href="#cb46-15" aria-hidden="true" tabindex="-1"></a>        <span class="co"># This observation has bad data</span></span>
-<span id="cb46-16"><a href="#cb46-16" aria-hidden="true" tabindex="-1"></a>       <span class="cf">return</span> <span class="va">None</span></span>
-<span id="cb46-17"><a href="#cb46-17" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb46-18"><a href="#cb46-18" aria-hidden="true" tabindex="-1"></a>calculate_life_quartile(<span class="fl">62.5</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb46-1"><a href="#cb46-1" tabindex="-1"></a><span class="kw">def</span> calculate_life_quartile(exp):</span>
+<span id="cb46-2"><a href="#cb46-2" tabindex="-1"></a>    <span class="cf">if</span> exp <span class="op">&lt;</span> <span class="fl">58.41</span>:</span>
+<span id="cb46-3"><a href="#cb46-3" tabindex="-1"></a>        <span class="co"># This observation is in the first quartile</span></span>
+<span id="cb46-4"><a href="#cb46-4" tabindex="-1"></a>        <span class="cf">return</span> <span class="dv">1</span></span>
+<span id="cb46-5"><a href="#cb46-5" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">58.41</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">67.05</span>:</span>
+<span id="cb46-6"><a href="#cb46-6" tabindex="-1"></a>        <span class="co"># This observation is in the second quartile</span></span>
+<span id="cb46-7"><a href="#cb46-7" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">2</span></span>
+<span id="cb46-8"><a href="#cb46-8" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">67.05</span> <span class="kw">and</span> exp <span class="op">&lt;</span> <span class="fl">71.70</span>:</span>
+<span id="cb46-9"><a href="#cb46-9" tabindex="-1"></a>        <span class="co"># This observation is in the third quartile</span></span>
+<span id="cb46-10"><a href="#cb46-10" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">3</span></span>
+<span id="cb46-11"><a href="#cb46-11" tabindex="-1"></a>    <span class="cf">elif</span> exp <span class="op">&gt;=</span> <span class="fl">71.70</span>:</span>
+<span id="cb46-12"><a href="#cb46-12" tabindex="-1"></a>        <span class="co"># This observation is in the fourth quartile</span></span>
+<span id="cb46-13"><a href="#cb46-13" tabindex="-1"></a>       <span class="cf">return</span> <span class="dv">4</span></span>
+<span id="cb46-14"><a href="#cb46-14" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb46-15"><a href="#cb46-15" tabindex="-1"></a>        <span class="co"># This observation has bad data</span></span>
+<span id="cb46-16"><a href="#cb46-16" tabindex="-1"></a>       <span class="cf">return</span> <span class="va">None</span></span>
+<span id="cb46-17"><a href="#cb46-17" tabindex="-1"></a></span>
+<span id="cb46-18"><a href="#cb46-18" tabindex="-1"></a>calculate_life_quartile(<span class="fl">62.5</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -9169,8 +9171,8 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb48">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" aria-hidden="true" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>)</span>
-<span id="cb48-2"><a href="#cb48-2" aria-hidden="true" tabindex="-1"></a>data[<span class="st">'life_qrtl'</span>] <span class="op">=</span> data[<span class="st">'lifeExp_1952'</span>].<span class="bu">apply</span>(calculate_life_quartile)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" tabindex="-1"></a>data <span class="op">=</span> pd.read_csv(<span class="st">'data/gapminder_all.csv'</span>)</span>
+<span id="cb48-2"><a href="#cb48-2" tabindex="-1"></a>data[<span class="st">'life_qrtl'</span>] <span class="op">=</span> data[<span class="st">'lifeExp_1952'</span>].<span class="bu">apply</span>(calculate_life_quartile)</span></code></pre>
 </div>
 <p>There is a lot in that second line, so let’s take it piece by piece.
 On the right side of the <code>=</code> we start with
@@ -9259,11 +9261,11 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">103.9</span></span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> adjust(t):</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    temperature <span class="op">=</span> t <span class="op">*</span> <span class="fl">1.43</span> <span class="op">/</span> pressure</span>
-<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> temperature</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a>pressure <span class="op">=</span> <span class="fl">103.9</span></span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a><span class="kw">def</span> adjust(t):</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    temperature <span class="op">=</span> t <span class="op">*</span> <span class="fl">1.43</span> <span class="op">/</span> pressure</span>
+<span id="cb1-5"><a href="#cb1-5" tabindex="-1"></a>    <span class="cf">return</span> temperature</span></code></pre>
 </div>
 <ul>
 <li>
@@ -9287,8 +9289,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'adjusted:'</span>, adjust(<span class="fl">0.9</span>))</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'temperature after call:'</span>, temperature)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'adjusted:'</span>, adjust(<span class="fl">0.9</span>))</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a><span class="bu">print</span>(<span class="st">'temperature after call:'</span>, temperature)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -9316,13 +9318,13 @@ <h3 class="callout-title">Local and Global Variable Use<a class="anchor" aria-la
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>limit <span class="op">=</span> <span class="dv">100</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> clip(value):</span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">min</span>(<span class="bu">max</span>(<span class="fl">0.0</span>, value), limit)</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a>value <span class="op">=</span> <span class="op">-</span><span class="fl">22.5</span></span>
-<span id="cb5-7"><a href="#cb5-7" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(clip(value))</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a>limit <span class="op">=</span> <span class="dv">100</span></span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a></span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a><span class="kw">def</span> clip(value):</span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">min</span>(<span class="bu">max</span>(<span class="fl">0.0</span>, value), limit)</span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a></span>
+<span id="cb5-6"><a href="#cb5-6" tabindex="-1"></a>value <span class="op">=</span> <span class="op">-</span><span class="fl">22.5</span></span>
+<span id="cb5-7"><a href="#cb5-7" tabindex="-1"></a><span class="bu">print</span>(clip(value))</span></code></pre>
 </div>
 </div>
 </div>
@@ -9375,7 +9377,7 @@ <h3 class="code-label">ERROR<i aria-hidden="true" data-feather="chevron-left"></
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
 <div class="accordion-body">
 <ol style="list-style-type: decimal">
 <li>Three levels.</li>
@@ -9499,10 +9501,10 @@ <h3 class="card-title">Objectives</h3>
 <div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> calc_bulk_density(mass, volume):</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">'''Return dry bulk density = powder mass / powder volume.'''</span></span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">assert</span> volume <span class="op">&gt;</span> <span class="dv">0</span></span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> mass <span class="op">/</span> volume</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="kw">def</span> calc_bulk_density(mass, volume):</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>    <span class="co">'''Return dry bulk density = powder mass / powder volume.'''</span></span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>    <span class="cf">assert</span> volume <span class="op">&gt;</span> <span class="dv">0</span></span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>    <span class="cf">return</span> mass <span class="op">/</span> volume</span></code></pre>
 </div>
 <p>If the assertion is <code>False</code>, the Python interpreter raises
 an <code>AssertionError</code> runtime exception. The source code for
@@ -9521,14 +9523,14 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">"Return average of values, or None if no values are supplied."</span></span>
-<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
-<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
-<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span>
-<span id="cb2-7"><a href="#cb2-7" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb2-8"><a href="#cb2-8" aria-hidden="true" tabindex="-1"></a><span class="bu">help</span>(average)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="kw">def</span> average(values):</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a>    <span class="co">"Return average of values, or None if no values are supplied."</span></span>
+<span id="cb2-3"><a href="#cb2-3" tabindex="-1"></a></span>
+<span id="cb2-4"><a href="#cb2-4" tabindex="-1"></a>    <span class="cf">if</span> <span class="bu">len</span>(values) <span class="op">==</span> <span class="dv">0</span>:</span>
+<span id="cb2-5"><a href="#cb2-5" tabindex="-1"></a>        <span class="cf">return</span> <span class="va">None</span></span>
+<span id="cb2-6"><a href="#cb2-6" tabindex="-1"></a>    <span class="cf">return</span> <span class="bu">sum</span>(values) <span class="op">/</span> <span class="bu">len</span>(values)</span>
+<span id="cb2-7"><a href="#cb2-7" tabindex="-1"></a></span>
+<span id="cb2-8"><a href="#cb2-8" tabindex="-1"></a><span class="bu">help</span>(average)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -9538,12 +9540,12 @@ <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"><
 average(values)
     Return average of values, or None if no values are supplied.</code></pre>
 </div>
-<div id="multiline-strings" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="multiline-strings" class="callout-inner">
-<h3 class="callout-title">Multiline Strings<a class="anchor" aria-label="anchor" href="#multiline-strings"></a>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="multiline-strings">Multiline Strings<a class="anchor" aria-label="anchor" href="#multiline-strings"></a>
 </h3>
 <div class="callout-content">
 <p>Often use <em>multiline strings</em> for documentation. These start
@@ -9552,10 +9554,10 @@ <h3 class="callout-title">Multiline Strings<a class="anchor" aria-label="anchor"
 <div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="co">"""This string spans</span></span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a><span class="co">multiple lines.</span></span>
-<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a><span class="co">Blank lines are allowed."""</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="co">"""This string spans</span></span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a><span class="co">multiple lines.</span></span>
+<span id="cb4-3"><a href="#cb4-3" tabindex="-1"></a></span>
+<span id="cb4-4"><a href="#cb4-4" tabindex="-1"></a><span class="co">Blank lines are allowed."""</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -9574,22 +9576,22 @@ <h3 class="callout-title">What Will Be Shown?<a class="anchor" aria-label="ancho
 <div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="co">"Find maximum edit distance between multiple sequences."</span></span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="co"># This finds the maximum distance between all sequences.</span></span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> overall_max(sequences):</span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>    <span class="co">'''Determine overall maximum edit distance.'''</span></span>
-<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-7"><a href="#cb5-7" aria-hidden="true" tabindex="-1"></a>    highest <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb5-8"><a href="#cb5-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> left <span class="kw">in</span> sequences:</span>
-<span id="cb5-9"><a href="#cb5-9" aria-hidden="true" tabindex="-1"></a>        <span class="cf">for</span> right <span class="kw">in</span> sequences:</span>
-<span id="cb5-10"><a href="#cb5-10" aria-hidden="true" tabindex="-1"></a>            <span class="co">'''Avoid checking sequence against itself.'''</span></span>
-<span id="cb5-11"><a href="#cb5-11" aria-hidden="true" tabindex="-1"></a>            <span class="cf">if</span> left <span class="op">!=</span> right:</span>
-<span id="cb5-12"><a href="#cb5-12" aria-hidden="true" tabindex="-1"></a>                this <span class="op">=</span> edit_distance(left, right)</span>
-<span id="cb5-13"><a href="#cb5-13" aria-hidden="true" tabindex="-1"></a>                highest <span class="op">=</span> <span class="bu">max</span>(highest, this)</span>
-<span id="cb5-14"><a href="#cb5-14" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-15"><a href="#cb5-15" aria-hidden="true" tabindex="-1"></a>    <span class="co"># Report.</span></span>
-<span id="cb5-16"><a href="#cb5-16" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> highest</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="co">"Find maximum edit distance between multiple sequences."</span></span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a><span class="co"># This finds the maximum distance between all sequences.</span></span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a></span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a><span class="kw">def</span> overall_max(sequences):</span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a>    <span class="co">'''Determine overall maximum edit distance.'''</span></span>
+<span id="cb5-6"><a href="#cb5-6" tabindex="-1"></a></span>
+<span id="cb5-7"><a href="#cb5-7" tabindex="-1"></a>    highest <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb5-8"><a href="#cb5-8" tabindex="-1"></a>    <span class="cf">for</span> left <span class="kw">in</span> sequences:</span>
+<span id="cb5-9"><a href="#cb5-9" tabindex="-1"></a>        <span class="cf">for</span> right <span class="kw">in</span> sequences:</span>
+<span id="cb5-10"><a href="#cb5-10" tabindex="-1"></a>            <span class="co">'''Avoid checking sequence against itself.'''</span></span>
+<span id="cb5-11"><a href="#cb5-11" tabindex="-1"></a>            <span class="cf">if</span> left <span class="op">!=</span> right:</span>
+<span id="cb5-12"><a href="#cb5-12" tabindex="-1"></a>                this <span class="op">=</span> edit_distance(left, right)</span>
+<span id="cb5-13"><a href="#cb5-13" tabindex="-1"></a>                highest <span class="op">=</span> <span class="bu">max</span>(highest, this)</span>
+<span id="cb5-14"><a href="#cb5-14" tabindex="-1"></a></span>
+<span id="cb5-15"><a href="#cb5-15" tabindex="-1"></a>    <span class="co"># Report.</span></span>
+<span id="cb5-16"><a href="#cb5-16" tabindex="-1"></a>    <span class="cf">return</span> highest</span></code></pre>
 </div>
 </div>
 </div>
@@ -9615,12 +9617,12 @@ <h3 class="callout-title">Document This<a class="anchor" aria-label="anchor" hre
 <div class="codewrapper sourceCode" id="cb6">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
-<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a>    <span class="co"># Return the middle value of three.</span></span>
-<span id="cb6-3"><a href="#cb6-3" aria-hidden="true" tabindex="-1"></a>    <span class="co"># Assumes the values can actually be compared.</span></span>
-<span id="cb6-4"><a href="#cb6-4" aria-hidden="true" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
-<span id="cb6-5"><a href="#cb6-5" aria-hidden="true" tabindex="-1"></a>    values.sort()</span>
-<span id="cb6-6"><a href="#cb6-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
+<span id="cb6-2"><a href="#cb6-2" tabindex="-1"></a>    <span class="co"># Return the middle value of three.</span></span>
+<span id="cb6-3"><a href="#cb6-3" tabindex="-1"></a>    <span class="co"># Assumes the values can actually be compared.</span></span>
+<span id="cb6-4"><a href="#cb6-4" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
+<span id="cb6-5"><a href="#cb6-5" tabindex="-1"></a>    values.sort()</span>
+<span id="cb6-6"><a href="#cb6-6" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -9630,17 +9632,17 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution1" aria-expanded="false" aria-controls="collapseSolution1">
   <h4 class="accordion-header" id="headingSolution1">Show me the solution</h4>
 </button>
-<div id="collapseSolution1" class="accordion-collapse collapse" data-bs-parent="#accordionSolution1" aria-labelledby="headingSolution1">
+<div id="collapseSolution1" class="accordion-collapse collapse" aria-labelledby="headingSolution1" data-bs-parent="#accordionSolution1">
 <div class="accordion-body">
 <div class="codewrapper sourceCode" id="cb7">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
-<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">'''Return the middle value of three.</span></span>
-<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a><span class="co">    Assumes the values can actually be compared.'''</span></span>
-<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
-<span id="cb7-5"><a href="#cb7-5" aria-hidden="true" tabindex="-1"></a>    values.sort()</span>
-<span id="cb7-6"><a href="#cb7-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" tabindex="-1"></a><span class="kw">def</span> middle(a, b, c):</span>
+<span id="cb7-2"><a href="#cb7-2" tabindex="-1"></a>    <span class="co">'''Return the middle value of three.</span></span>
+<span id="cb7-3"><a href="#cb7-3" tabindex="-1"></a><span class="co">    Assumes the values can actually be compared.'''</span></span>
+<span id="cb7-4"><a href="#cb7-4" tabindex="-1"></a>    values <span class="op">=</span> [a, b, c]</span>
+<span id="cb7-5"><a href="#cb7-5" tabindex="-1"></a>    values.sort()</span>
+<span id="cb7-6"><a href="#cb7-6" tabindex="-1"></a>    <span class="cf">return</span> values[<span class="dv">1</span>]</span></code></pre>
 </div>
 </div>
 </div>
@@ -9665,21 +9667,21 @@ <h3 class="callout-title">Clean Up This Code<a class="anchor" aria-label="anchor
 <div class="codewrapper sourceCode" id="cb8">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a>n <span class="op">=</span> <span class="dv">10</span></span>
-<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>s <span class="op">=</span> <span class="st">'et cetera'</span></span>
-<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a><span class="bu">print</span>(s)</span>
-<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
-<span id="cb8-5"><a href="#cb8-5" aria-hidden="true" tabindex="-1"></a><span class="cf">while</span> i <span class="op">&lt;</span> n:</span>
-<span id="cb8-6"><a href="#cb8-6" aria-hidden="true" tabindex="-1"></a>    <span class="co"># print('at', j)</span></span>
-<span id="cb8-7"><a href="#cb8-7" aria-hidden="true" tabindex="-1"></a>    new <span class="op">=</span> <span class="st">''</span></span>
-<span id="cb8-8"><a href="#cb8-8" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(<span class="bu">len</span>(s)):</span>
-<span id="cb8-9"><a href="#cb8-9" aria-hidden="true" tabindex="-1"></a>        left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
-<span id="cb8-10"><a href="#cb8-10" aria-hidden="true" tabindex="-1"></a>        right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>)<span class="op">%</span><span class="bu">len</span>(s)</span>
-<span id="cb8-11"><a href="#cb8-11" aria-hidden="true" tabindex="-1"></a>        <span class="cf">if</span> s[left]<span class="op">==</span>s[right]: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
-<span id="cb8-12"><a href="#cb8-12" aria-hidden="true" tabindex="-1"></a>        <span class="cf">else</span>: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
-<span id="cb8-13"><a href="#cb8-13" aria-hidden="true" tabindex="-1"></a>    s<span class="op">=</span><span class="st">''</span>.join(new)</span>
-<span id="cb8-14"><a href="#cb8-14" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(s)</span>
-<span id="cb8-15"><a href="#cb8-15" aria-hidden="true" tabindex="-1"></a>    i <span class="op">+=</span> <span class="dv">1</span></span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" tabindex="-1"></a>n <span class="op">=</span> <span class="dv">10</span></span>
+<span id="cb8-2"><a href="#cb8-2" tabindex="-1"></a>s <span class="op">=</span> <span class="st">'et cetera'</span></span>
+<span id="cb8-3"><a href="#cb8-3" tabindex="-1"></a><span class="bu">print</span>(s)</span>
+<span id="cb8-4"><a href="#cb8-4" tabindex="-1"></a>i <span class="op">=</span> <span class="dv">0</span></span>
+<span id="cb8-5"><a href="#cb8-5" tabindex="-1"></a><span class="cf">while</span> i <span class="op">&lt;</span> n:</span>
+<span id="cb8-6"><a href="#cb8-6" tabindex="-1"></a>    <span class="co"># print('at', j)</span></span>
+<span id="cb8-7"><a href="#cb8-7" tabindex="-1"></a>    new <span class="op">=</span> <span class="st">''</span></span>
+<span id="cb8-8"><a href="#cb8-8" tabindex="-1"></a>    <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(<span class="bu">len</span>(s)):</span>
+<span id="cb8-9"><a href="#cb8-9" tabindex="-1"></a>        left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
+<span id="cb8-10"><a href="#cb8-10" tabindex="-1"></a>        right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>)<span class="op">%</span><span class="bu">len</span>(s)</span>
+<span id="cb8-11"><a href="#cb8-11" tabindex="-1"></a>        <span class="cf">if</span> s[left]<span class="op">==</span>s[right]: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
+<span id="cb8-12"><a href="#cb8-12" tabindex="-1"></a>        <span class="cf">else</span>: new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
+<span id="cb8-13"><a href="#cb8-13" tabindex="-1"></a>    s<span class="op">=</span><span class="st">''</span>.join(new)</span>
+<span id="cb8-14"><a href="#cb8-14" tabindex="-1"></a>    <span class="bu">print</span>(s)</span>
+<span id="cb8-15"><a href="#cb8-15" tabindex="-1"></a>    i <span class="op">+=</span> <span class="dv">1</span></span></code></pre>
 </div>
 </div>
 </div>
@@ -9689,37 +9691,37 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 <button class="accordion-button solution-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#collapseSolution2" aria-expanded="false" aria-controls="collapseSolution2">
   <h4 class="accordion-header" id="headingSolution2">Show me the solution</h4>
 </button>
-<div id="collapseSolution2" class="accordion-collapse collapse" data-bs-parent="#accordionSolution2" aria-labelledby="headingSolution2">
+<div id="collapseSolution2" class="accordion-collapse collapse" aria-labelledby="headingSolution2" data-bs-parent="#accordionSolution2">
 <div class="accordion-body">
 <p>Here’s one solution.</p>
 <div class="codewrapper sourceCode" id="cb9">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> string_machine(input_string, iterations):</span>
-<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a>    <span class="co">"""</span></span>
-<span id="cb9-3"><a href="#cb9-3" aria-hidden="true" tabindex="-1"></a><span class="co">    Takes input_string and generates a new string with -'s and *'s</span></span>
-<span id="cb9-4"><a href="#cb9-4" aria-hidden="true" tabindex="-1"></a><span class="co">    corresponding to characters that have identical adjacent characters</span></span>
-<span id="cb9-5"><a href="#cb9-5" aria-hidden="true" tabindex="-1"></a><span class="co">    or not, respectively.  Iterates through this procedure with the resultant</span></span>
-<span id="cb9-6"><a href="#cb9-6" aria-hidden="true" tabindex="-1"></a><span class="co">    strings for the supplied number of iterations.</span></span>
-<span id="cb9-7"><a href="#cb9-7" aria-hidden="true" tabindex="-1"></a><span class="co">    """</span></span>
-<span id="cb9-8"><a href="#cb9-8" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(input_string)</span>
-<span id="cb9-9"><a href="#cb9-9" aria-hidden="true" tabindex="-1"></a>    input_string_length <span class="op">=</span> <span class="bu">len</span>(input_string)</span>
-<span id="cb9-10"><a href="#cb9-10" aria-hidden="true" tabindex="-1"></a>    old <span class="op">=</span> input_string</span>
-<span id="cb9-11"><a href="#cb9-11" aria-hidden="true" tabindex="-1"></a>    <span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(iterations):</span>
-<span id="cb9-12"><a href="#cb9-12" aria-hidden="true" tabindex="-1"></a>        new <span class="op">=</span> <span class="st">''</span></span>
-<span id="cb9-13"><a href="#cb9-13" aria-hidden="true" tabindex="-1"></a>        <span class="co"># iterate through characters in previous string</span></span>
-<span id="cb9-14"><a href="#cb9-14" aria-hidden="true" tabindex="-1"></a>        <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(input_string_length):</span>
-<span id="cb9-15"><a href="#cb9-15" aria-hidden="true" tabindex="-1"></a>            left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
-<span id="cb9-16"><a href="#cb9-16" aria-hidden="true" tabindex="-1"></a>            right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>) <span class="op">%</span> input_string_length  <span class="co"># ensure right index wraps around</span></span>
-<span id="cb9-17"><a href="#cb9-17" aria-hidden="true" tabindex="-1"></a>            <span class="cf">if</span> old[left] <span class="op">==</span> old[right]:</span>
-<span id="cb9-18"><a href="#cb9-18" aria-hidden="true" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
-<span id="cb9-19"><a href="#cb9-19" aria-hidden="true" tabindex="-1"></a>            <span class="cf">else</span>:</span>
-<span id="cb9-20"><a href="#cb9-20" aria-hidden="true" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
-<span id="cb9-21"><a href="#cb9-21" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(new)</span>
-<span id="cb9-22"><a href="#cb9-22" aria-hidden="true" tabindex="-1"></a>        <span class="co"># store new string as old</span></span>
-<span id="cb9-23"><a href="#cb9-23" aria-hidden="true" tabindex="-1"></a>        old <span class="op">=</span> new     </span>
-<span id="cb9-24"><a href="#cb9-24" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb9-25"><a href="#cb9-25" aria-hidden="true" tabindex="-1"></a>string_machine(<span class="st">'et cetera'</span>, <span class="dv">10</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" tabindex="-1"></a><span class="kw">def</span> string_machine(input_string, iterations):</span>
+<span id="cb9-2"><a href="#cb9-2" tabindex="-1"></a>    <span class="co">"""</span></span>
+<span id="cb9-3"><a href="#cb9-3" tabindex="-1"></a><span class="co">    Takes input_string and generates a new string with -'s and *'s</span></span>
+<span id="cb9-4"><a href="#cb9-4" tabindex="-1"></a><span class="co">    corresponding to characters that have identical adjacent characters</span></span>
+<span id="cb9-5"><a href="#cb9-5" tabindex="-1"></a><span class="co">    or not, respectively.  Iterates through this procedure with the resultant</span></span>
+<span id="cb9-6"><a href="#cb9-6" tabindex="-1"></a><span class="co">    strings for the supplied number of iterations.</span></span>
+<span id="cb9-7"><a href="#cb9-7" tabindex="-1"></a><span class="co">    """</span></span>
+<span id="cb9-8"><a href="#cb9-8" tabindex="-1"></a>    <span class="bu">print</span>(input_string)</span>
+<span id="cb9-9"><a href="#cb9-9" tabindex="-1"></a>    input_string_length <span class="op">=</span> <span class="bu">len</span>(input_string)</span>
+<span id="cb9-10"><a href="#cb9-10" tabindex="-1"></a>    old <span class="op">=</span> input_string</span>
+<span id="cb9-11"><a href="#cb9-11" tabindex="-1"></a>    <span class="cf">for</span> i <span class="kw">in</span> <span class="bu">range</span>(iterations):</span>
+<span id="cb9-12"><a href="#cb9-12" tabindex="-1"></a>        new <span class="op">=</span> <span class="st">''</span></span>
+<span id="cb9-13"><a href="#cb9-13" tabindex="-1"></a>        <span class="co"># iterate through characters in previous string</span></span>
+<span id="cb9-14"><a href="#cb9-14" tabindex="-1"></a>        <span class="cf">for</span> j <span class="kw">in</span> <span class="bu">range</span>(input_string_length):</span>
+<span id="cb9-15"><a href="#cb9-15" tabindex="-1"></a>            left <span class="op">=</span> j<span class="op">-</span><span class="dv">1</span></span>
+<span id="cb9-16"><a href="#cb9-16" tabindex="-1"></a>            right <span class="op">=</span> (j<span class="op">+</span><span class="dv">1</span>) <span class="op">%</span> input_string_length  <span class="co"># ensure right index wraps around</span></span>
+<span id="cb9-17"><a href="#cb9-17" tabindex="-1"></a>            <span class="cf">if</span> old[left] <span class="op">==</span> old[right]:</span>
+<span id="cb9-18"><a href="#cb9-18" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'-'</span></span>
+<span id="cb9-19"><a href="#cb9-19" tabindex="-1"></a>            <span class="cf">else</span>:</span>
+<span id="cb9-20"><a href="#cb9-20" tabindex="-1"></a>                new <span class="op">=</span> new <span class="op">+</span> <span class="st">'*'</span></span>
+<span id="cb9-21"><a href="#cb9-21" tabindex="-1"></a>        <span class="bu">print</span>(new)</span>
+<span id="cb9-22"><a href="#cb9-22" tabindex="-1"></a>        <span class="co"># store new string as old</span></span>
+<span id="cb9-23"><a href="#cb9-23" tabindex="-1"></a>        old <span class="op">=</span> new     </span>
+<span id="cb9-24"><a href="#cb9-24" tabindex="-1"></a></span>
+<span id="cb9-25"><a href="#cb9-25" tabindex="-1"></a>string_machine(<span class="st">'et cetera'</span>, <span class="dv">10</span>)</span></code></pre>
 </div>
 <div class="codewrapper">
 <h3 class="code-label">OUTPUT<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
@@ -9928,8 +9930,8 @@ <h3 class="callout-title">Key Points<a class="anchor" aria-label="anchor" href="
   "url": "https://swcarpentry.github.io/python-novice-gapminder/instructor/aio.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/aio.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/design.html b/instructor/design.html
index 5a90f8c90..717936958 100644
--- a/instructor/design.html
+++ b/instructor/design.html
@@ -388,13 +388,12 @@ <h1>Lesson Design</h1>
 
         
 
-<div id="help-wanted" class="callout callout">
+<div id="callout1" class="callout">
 <div class="callout-square">
 <i class="callout-icon" data-feather="bell"></i>
 </div>
-<div id="help-wanted" class="callout-inner">
-<h3 class="callout-title">Help Wanted<a class="anchor" aria-label="anchor" href="#help-wanted"></a>
-</h3>
+<div class="section level3 callout-title callout-inner">
+<h3 class="callout-title" id="help-wanted">Help Wanted<a class="anchor" aria-label="anchor" href="#help-wanted"></a></h3>
 <div class="callout-content">
 <p><strong>We are filling in the exercises <a href="#stage-3-learning-plan">below</a> in order to make the lesson plan
 more concrete. Contributions (both in the form of pull requests with
@@ -942,7 +941,7 @@ <h3 id="finish-1630">Finish (16:30)<a class="anchor" aria-label="anchor" href="#
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/design.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/discuss.html b/instructor/discuss.html
index 96fbca7d3..a034d4c5f 100644
--- a/instructor/discuss.html
+++ b/instructor/discuss.html
@@ -449,7 +449,7 @@ <h1>Discussion</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/discuss.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/exercises.html b/instructor/exercises.html
index 353f667f8..db3c3c1fd 100644
--- a/instructor/exercises.html
+++ b/instructor/exercises.html
@@ -449,7 +449,7 @@ <h1>Further Exercises</h1>
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/exercises.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-05-02",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/images.html b/instructor/images.html
index 81ef64f21..c9c615d09 100644
--- a/instructor/images.html
+++ b/instructor/images.html
@@ -512,10 +512,11 @@ <h3 id="01-run-quit-figure-7">Figure 7</h3>
 <hr></section><section id="02-variables"><h2 class="section-heading"><a href="02-variables.html">Variables and Assignment</a></h2>
 <hr class="half-width">
 <h3 id="02-variables-figure-1">Figure 1</h3>
-<p aria-hidden="true">Image 1 of 1: ‘[decorative]’</p>
-<figure><img src="../fig/2_indexing.svg" alt="" class="figure mx-auto d-block"><figcaption>A line of Python code, print(atom_name[0]),
+<p aria-hidden="true">Image 1 of 1: ‘A line of Python code, print(atom_name[0]), demonstrates that using the zero index will output just the initial letter, in this case ‘h’ for helium.’</p>
+<figure><img src="../fig/2_indexing.svg" alt="A line of Python code, print(atom_name[0]), demonstrates that using the zero index will output just the initial letter, in this case ‘h’ for helium." class="figure mx-auto d-block"><div class="figcaption">A line of Python code, print(atom_name[0]),
 demonstrates that using the zero index will output just the initial
-letter, in this case ‘h’ for helium.</figcaption></figure><hr></section><section id="03-types-conversion"><h2 class="section-heading"><a href="03-types-conversion.html">Data Types and Type Conversion</a></h2>
+letter, in this case ‘h’ for helium.</div>
+</figure><hr></section><section id="03-types-conversion"><h2 class="section-heading"><a href="03-types-conversion.html">Data Types and Type Conversion</a></h2>
 <hr class="half-width"></section><section id="04-built-in"><h2 class="section-heading"><a href="04-built-in.html">Built-in Functions and Help</a></h2>
 <hr class="half-width"></section><section id="05-coffee"><h2 class="section-heading"><a href="05-coffee.html">Morning Coffee</a></h2>
 <hr class="half-width"></section><section id="06-libraries"><h2 class="section-heading"><a href="06-libraries.html">Libraries</a></h2>
@@ -617,8 +618,8 @@ <h3 id="09-plotting-figure-12">Figure 12</h3>
   "url": "https://swcarpentry.github.io/python-novice-gapminder/instructor/images.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/images.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/index.html b/instructor/index.html
index b0383a62e..00a86d703 100644
--- a/instructor/index.html
+++ b/instructor/index.html
@@ -653,8 +653,8 @@ <h3 class="callout-title">Prerequisites<a class="anchor" aria-label="anchor" hre
   "url": "https://swcarpentry.github.io/python-novice-gapminder/instructor/index.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/index.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/instructor-notes.html b/instructor/instructor-notes.html
index d59e6df7c..9d6725637 100644
--- a/instructor/instructor-notes.html
+++ b/instructor/instructor-notes.html
@@ -578,8 +578,8 @@ <h3 id="08-data-frames-headingInstructor1">
   "url": "https://swcarpentry.github.io/python-novice-gapminder/instructor/instructor-notes.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/instructor-notes.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/key-points.html b/instructor/key-points.html
index 2a071566b..9881b924a 100644
--- a/instructor/key-points.html
+++ b/instructor/key-points.html
@@ -708,8 +708,8 @@ <h2 class="accordion-header" id="flush-headingTwelve">
   "url": "https://swcarpentry.github.io/python-novice-gapminder/instructor/key-points.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/key-points.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/profiles.html b/instructor/profiles.html
index f7ede838c..e9a60b8b2 100644
--- a/instructor/profiles.html
+++ b/instructor/profiles.html
@@ -405,8 +405,8 @@ <h1>Learner Profiles</h1>
   "url": "https://swcarpentry.github.io/python-novice-gapminder/instructor/profiles.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/profiles.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/instructor/reference.html b/instructor/reference.html
index a2c15ab93..994690b05 100644
--- a/instructor/reference.html
+++ b/instructor/reference.html
@@ -566,11 +566,11 @@ <h1>Reference</h1>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> matplotlib.puplot <span class="im">as</span> plot</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>plt.plot(time, position, label<span class="op">=</span><span class="st">'label'</span>)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>plt.xlabel(<span class="st">'x axis label'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'y axis label'</span>)</span>
-<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a>plt.legend()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> matplotlib.puplot <span class="im">as</span> plot</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>plt.plot(time, position, label<span class="op">=</span><span class="st">'label'</span>)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>plt.xlabel(<span class="st">'x axis label'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>plt.ylabel(<span class="st">'y axis label'</span>)</span>
+<span id="cb1-5"><a href="#cb1-5" tabindex="-1"></a>plt.legend()</span></code></pre>
 </div>
 </section><section id="lists"><h2 class="section-heading">
 <a href="11-lists.html">Lists</a><a class="anchor" aria-label="anchor" href="#lists"></a>
@@ -607,8 +607,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>,<span class="dv">5</span>):</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>,<span class="dv">5</span>):</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 </section><section id="conditionals"><h2 class="section-heading">
 <a href="13-conditionals.html">Conditionals</a><a class="anchor" aria-label="anchor" href="#conditionals"></a>
@@ -637,13 +637,13 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> [<span class="dv">3</span>, <span class="dv">6</span>, <span class="dv">7</span>, <span class="dv">2</span>, <span class="dv">8</span>]:</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="dv">5</span>:</span>
-<span id="cb3-3"><a href="#cb3-3" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
-<span id="cb3-4"><a href="#cb3-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> m <span class="op">==</span> <span class="dv">5</span>:</span>
-<span id="cb3-5"><a href="#cb3-5" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is 5'</span>)</span>
-<span id="cb3-6"><a href="#cb3-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb3-7"><a href="#cb3-7" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> [<span class="dv">3</span>, <span class="dv">6</span>, <span class="dv">7</span>, <span class="dv">2</span>, <span class="dv">8</span>]:</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="dv">5</span>:</span>
+<span id="cb3-3"><a href="#cb3-3" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
+<span id="cb3-4"><a href="#cb3-4" tabindex="-1"></a>    <span class="cf">elif</span> m <span class="op">==</span> <span class="dv">5</span>:</span>
+<span id="cb3-5"><a href="#cb3-5" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is 5'</span>)</span>
+<span id="cb3-6"><a href="#cb3-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb3-7"><a href="#cb3-7" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
 </div>
 </section><section id="looping-over-data-sets"><h2 class="section-heading">
 <a href="14-looping-data-sets.html">Looping Over Data Sets</a><a class="anchor" aria-label="anchor" href="#looping-over-data-sets"></a>
@@ -666,8 +666,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="op">*</span>.txt):</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>  data <span class="op">=</span> pd.read_csv(filename)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="op">*</span>.txt):</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a>  data <span class="op">=</span> pd.read_csv(filename)</span></code></pre>
 </div>
 </section><section id="writing-functions"><h2 class="section-heading">
 <a href="16-writing-functions.html">Writing Functions</a><a class="anchor" aria-label="anchor" href="#writing-functions"></a>
@@ -681,11 +681,11 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> add_numbers(a, b):</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> a <span class="op">+</span> b</span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> result</span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>add_numbers(<span class="dv">1</span>, <span class="dv">4</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="kw">def</span> add_numbers(a, b):</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a>    result <span class="op">=</span> a <span class="op">+</span> b</span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a>    <span class="cf">return</span> result</span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a></span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a>add_numbers(<span class="dv">1</span>, <span class="dv">4</span>)</span></code></pre>
 </div>
 </section><section id="variable-scope"><h2 class="section-heading">
 <a href="17-scope.html">Variable Scope</a><a class="anchor" aria-label="anchor" href="#variable-scope"></a>
@@ -840,7 +840,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/instructor/reference.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-08-19",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/key-points.html b/key-points.html
index 2526e6ffd..598d2a859 100644
--- a/key-points.html
+++ b/key-points.html
@@ -704,8 +704,8 @@ <h2 class="accordion-header" id="flush-headingTwelve">
   "url": "https://swcarpentry.github.io/python-novice-gapminder/key-points.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/key-points.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/pkgdown.yml b/pkgdown.yml
index 181232b34..5b25dc419 100644
--- a/pkgdown.yml
+++ b/pkgdown.yml
@@ -1,6 +1,6 @@
-pandoc: 2.19.2
+pandoc: 3.1.11
 pkgdown: 2.0.7
 pkgdown_sha: ~
 articles: {}
-last_built: 2024-02-27T00:09Z
+last_built: 2024-03-05T00:08Z
 
diff --git a/profiles.html b/profiles.html
index 2d0b53623..609924fea 100644
--- a/profiles.html
+++ b/profiles.html
@@ -405,8 +405,8 @@ <h1>Learner Profiles</h1>
   "url": "https://swcarpentry.github.io/python-novice-gapminder/profiles.html",
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/profiles.html",
   "dateCreated": "2016-01-07",
-  "dateModified": "2024-02-27",
-  "datePublished": "2024-02-27"
+  "dateModified": "2024-03-05",
+  "datePublished": "2024-03-05"
 }
 
   </script><script>
diff --git a/reference.html b/reference.html
index 9aee37d80..2b226537a 100644
--- a/reference.html
+++ b/reference.html
@@ -564,11 +564,11 @@ <h1>Reference</h1>
 </ul><div class="codewrapper sourceCode" id="cb1">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="im">import</span> matplotlib.puplot <span class="im">as</span> plot</span>
-<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>plt.plot(time, position, label<span class="op">=</span><span class="st">'label'</span>)</span>
-<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>plt.xlabel(<span class="st">'x axis label'</span>)</span>
-<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>plt.ylabel(<span class="st">'y axis label'</span>)</span>
-<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a>plt.legend()</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" tabindex="-1"></a><span class="im">import</span> matplotlib.puplot <span class="im">as</span> plot</span>
+<span id="cb1-2"><a href="#cb1-2" tabindex="-1"></a>plt.plot(time, position, label<span class="op">=</span><span class="st">'label'</span>)</span>
+<span id="cb1-3"><a href="#cb1-3" tabindex="-1"></a>plt.xlabel(<span class="st">'x axis label'</span>)</span>
+<span id="cb1-4"><a href="#cb1-4" tabindex="-1"></a>plt.ylabel(<span class="st">'y axis label'</span>)</span>
+<span id="cb1-5"><a href="#cb1-5" tabindex="-1"></a>plt.legend()</span></code></pre>
 </div>
 </section><section id="lists"><h2 class="section-heading">
 <a href="11-lists.html">Lists</a><a class="anchor" aria-label="anchor" href="#lists"></a>
@@ -605,8 +605,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb2">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>,<span class="dv">5</span>):</span>
-<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" tabindex="-1"></a><span class="cf">for</span> number <span class="kw">in</span> <span class="bu">range</span>(<span class="dv">0</span>,<span class="dv">5</span>):</span>
+<span id="cb2-2"><a href="#cb2-2" tabindex="-1"></a>    <span class="bu">print</span>(number)</span></code></pre>
 </div>
 </section><section id="conditionals"><h2 class="section-heading">
 <a href="13-conditionals.html">Conditionals</a><a class="anchor" aria-label="anchor" href="#conditionals"></a>
@@ -635,13 +635,13 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb3">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> [<span class="dv">3</span>, <span class="dv">6</span>, <span class="dv">7</span>, <span class="dv">2</span>, <span class="dv">8</span>]:</span>
-<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="dv">5</span>:</span>
-<span id="cb3-3"><a href="#cb3-3" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
-<span id="cb3-4"><a href="#cb3-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">elif</span> m <span class="op">==</span> <span class="dv">5</span>:</span>
-<span id="cb3-5"><a href="#cb3-5" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is 5'</span>)</span>
-<span id="cb3-6"><a href="#cb3-6" aria-hidden="true" tabindex="-1"></a>    <span class="cf">else</span>:</span>
-<span id="cb3-7"><a href="#cb3-7" aria-hidden="true" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" tabindex="-1"></a><span class="cf">for</span> m <span class="kw">in</span> [<span class="dv">3</span>, <span class="dv">6</span>, <span class="dv">7</span>, <span class="dv">2</span>, <span class="dv">8</span>]:</span>
+<span id="cb3-2"><a href="#cb3-2" tabindex="-1"></a>    <span class="cf">if</span> m <span class="op">&gt;</span> <span class="dv">5</span>:</span>
+<span id="cb3-3"><a href="#cb3-3" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is large'</span>)</span>
+<span id="cb3-4"><a href="#cb3-4" tabindex="-1"></a>    <span class="cf">elif</span> m <span class="op">==</span> <span class="dv">5</span>:</span>
+<span id="cb3-5"><a href="#cb3-5" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is 5'</span>)</span>
+<span id="cb3-6"><a href="#cb3-6" tabindex="-1"></a>    <span class="cf">else</span>:</span>
+<span id="cb3-7"><a href="#cb3-7" tabindex="-1"></a>        <span class="bu">print</span>(m, <span class="st">'is small'</span>)</span></code></pre>
 </div>
 </section><section id="looping-over-data-sets"><h2 class="section-heading">
 <a href="14-looping-data-sets.html">Looping Over Data Sets</a><a class="anchor" aria-label="anchor" href="#looping-over-data-sets"></a>
@@ -664,8 +664,8 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb4">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="op">*</span>.txt):</span>
-<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>  data <span class="op">=</span> pd.read_csv(filename)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" tabindex="-1"></a><span class="cf">for</span> filename <span class="kw">in</span> glob.glob(<span class="op">*</span>.txt):</span>
+<span id="cb4-2"><a href="#cb4-2" tabindex="-1"></a>  data <span class="op">=</span> pd.read_csv(filename)</span></code></pre>
 </div>
 </section><section id="writing-functions"><h2 class="section-heading">
 <a href="16-writing-functions.html">Writing Functions</a><a class="anchor" aria-label="anchor" href="#writing-functions"></a>
@@ -679,11 +679,11 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
 </ul><div class="codewrapper sourceCode" id="cb5">
 <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"></i><i aria-hidden="true" data-feather="chevron-right"></i>
 </h3>
-<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> add_numbers(a, b):</span>
-<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a>    result <span class="op">=</span> a <span class="op">+</span> b</span>
-<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> result</span>
-<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a></span>
-<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>add_numbers(<span class="dv">1</span>, <span class="dv">4</span>)</span></code></pre>
+<pre class="sourceCode python" tabindex="0"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" tabindex="-1"></a><span class="kw">def</span> add_numbers(a, b):</span>
+<span id="cb5-2"><a href="#cb5-2" tabindex="-1"></a>    result <span class="op">=</span> a <span class="op">+</span> b</span>
+<span id="cb5-3"><a href="#cb5-3" tabindex="-1"></a>    <span class="cf">return</span> result</span>
+<span id="cb5-4"><a href="#cb5-4" tabindex="-1"></a></span>
+<span id="cb5-5"><a href="#cb5-5" tabindex="-1"></a>add_numbers(<span class="dv">1</span>, <span class="dv">4</span>)</span></code></pre>
 </div>
 </section><section id="variable-scope"><h2 class="section-heading">
 <a href="17-scope.html">Variable Scope</a><a class="anchor" aria-label="anchor" href="#variable-scope"></a>
@@ -838,7 +838,7 @@ <h3 class="code-label">PYTHON<i aria-hidden="true" data-feather="chevron-left"><
   "identifier": "https://swcarpentry.github.io/python-novice-gapminder/reference.html",
   "dateCreated": "2016-01-07",
   "dateModified": "2023-08-19",
-  "datePublished": "2024-02-27"
+  "datePublished": "2024-03-05"
 }
 
   </script><script>