def remove(self, elem):
        """Remove a requirement.

        :param elem: a string or :class:`Requirement` instance.
        """
        if isinstance(elem, text_type):
            for requirement in self:
                if requirement.package == elem:
                    return super(Requirements, self).remove(requirement)
        return super(Requirements, self).remove(elem)
def test_regex_good_input():
    cases = (
        '123',
        '1234567890',
        '00000',
    )

    num_only = inputs.regex(r'^[0-9]+$')

    for value in cases:
        yield assert_equal, num_only(value), value