def add(x, y):
    '''
    (int, int) -> int

    Returns addition of two integers

    REQ -> none

    >>> add(2,3)
    5
    >>> add(51, 29)
    80
    >>> add(1,5)
    6
    >>> add(96, 2)
    98
    '''
    return x+y


def double_number(x):
    '''
    (int) -> int

    Doubles the value of the number entered

    REQ -> none

    >>> double_number(3)
    6
    >>> double_number(21)
    42
    >>> double_number(100)
    200
    '''
    return x*2


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