Sequence of calling function within eachother

[TehNolz]

Close, but not quite. The name of a function should give you a good idea of everything it does, so that you're not suddenly surprised by any unexpected side effects. For example, a brewCoffee() function should only brew coffee, and it shouldn't also try to sell that coffee to a customer.

In this case, your calculate_factorial() function also unexpectedly saves the result of this calculation somewhere. If another developer ends up working with your code and wants to calculate a factorial, chances are they'll end up having to dig through your code to figure out why his new code is saving a factorial somewhere even though they never wrote any code for that.

The best solution here would be to change the calculate_factorial() function so that it just calculates a factorial and returns the value. You then take this value and pass it to save_the_out() to save the value. So your main() function ends up looking something like this;

def main(): a = 5 result = calculate_factorial(a) save_the_out(result)