Missing “return” at the end of the function Python

Question

Quite a stupid question but...

def gcd(a, b):
    if a < b:
        a, b = b, a
    if a == 0:
        return b
    elif b == 0:
        return a
    return gcd(b, a % b)

So when there's no return at the end of the function, why would the code return None ? When it's called recursively and a or b is eventually equal to 0 , it meets the if condition right? Then it should return the non-zero value.

Answer 1

If neither a nor b is equal to zero, neither one of the first two return statements will be executed.

Without the final return, the flow of control reaches the end of the function without hitting a return statement, so the default value of None is returned.