Multiply two integers without using the * operator

Multiply two integers without using the * operator.

def multiply(x, y):

    if y < 0:
        return -multiply(x, -y)
    elif y == 0:
        return 0
    elif y == 1:
        return x
    else:
        return x + multiply(x, y - 1)

# test
print(multiply(3, 5));

Output:

15

See also

https://www.w3resource.com/python-exercises/math/python-math-exercise-19.php