Stochastic functionality

[vvoovv]

Use case. Place an air conditioner in 30% of windows, a flower box in 20% of windows and both an air conditioner and a flower box in the rest of cases.

The proposed solution:

@rule
def Window()
    if pct(30):
        AirConditioner()
    elif pct(20):
        FlowerBox():
    elif pct():
        AirConditioner()
        FlowerBox():

pct is abbreviation for percent.

pct() without argument means "for the rest of cases". It also cleans up the internal stuff responsible for random values and makes it ready for the next usage.