arithmetic.py

def add(x, y):
    return x + y

def division(x, y):
    return x / y

def multiply(x, y):
    return x * y

def subtract(x, y):
    return x - y


if __name__ == '__main__':
    
    print('Testing...')
    
    assert add(1, 2) == 3
    assert division(1, 2) == 0.5
    assert multiply(4, 3) == 12
    assert subtract(5, 3) == 2
    
    print('...done!')