doctest

def div(a, b):
    """ a division function

    >>> div(4, 2)
    2.0
    >>> div(1, 0)
    Traceback (most recent call last):
        ...
    ZeroDivisionError: division by zero
    """
    return a / b

try:
    a = input('Please input a number a: ')
    b = input('Please input a number b: ')
    print(div(int(a), int(b)))
except ZeroDivisionError as Err:
    print('Error: ', Err)


if __name__ == ('__main__'):
    import doctest
    doctest.testmod()