doctest

#!/usr/bin/env python3

def sum(a, b):
    """
    >>> sum(4, 3)
    7

    >>> sum (-4, 5)
    1

    :param a:
    :param b:
    :return:
    """
    return a + b


def main():
    print("{} = {}".format("sum(3, 4)", sum(4, 3)))
    print("{} = {}".format("sum(-4, 5)", sum(-4, 5)))


if __name__ == '__main__':
    main()