More test programs/scripts

[Electrux]

Ethereal needs more test scripts for validating if the interpreter runs correctly.
You can write programs ranging from algorithms and data structures, to simple scripts performing some tasks and put those scripts in the tests/ directory.
Do comment here which program will you be writing so no one else works on it and verify that the program you are writing isn't already written in the tests/ directory.

Ideally, you would run the script with valgrind to verify if there are any memory leaks or not, but this is only possible for Linux users since macOS gives false positives with valgrind.

Please see CONTRIBUTING.md for code guidelines, and if you are working on algorithms/data structures, please see bubble sort implementation and binary search tree implementation.

Other issues, suggestions and contributions are always welcome. 😃
Happy coding! ❤️