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 check_url_error_message(value):
    try:
        inputs.url(value)
        assert False, u"inputs.url({0}) should raise an exception".format(value)
    except ValueError as e:
        assert_equal(six.text_type(e),
                     (u"{0} is not a valid URL. Did you mean: http://{0}".format(value)))