maths.py

def add(a, b):
    return a + b

def sub(a, b):
    return a - b


def sign(n, zero=1):
    if not n:
        return zero
    return n / abs(n)


def mul(a, b):
    c = 0
    for _ in range(b):
        c += a
    return c

def square(a):
    
    return a*a


if __name__ == '__main__':
    import sys
    if '--test' in sys.argv:
        assert add(0, 0) == 0
        assert add(20, 10) == 30
        assert sub(0, 0) == 0
        assert sub(1, 0) == 1
        assert sub(0, 1) == -1
        assert sign(1) == 1
        assert sign(-1) == -1
        assert mul(1, 0) == 0
        assert mul(0, 1) == 0
        assert mul(2, 6) == 12
        assert square(0.5) == 0.25
        assert square(2) == 4
        assert square(0) == 0