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 matchfn(self, f):
        # XXX: is_dir is set to True here for performance.
        # It should be set to whether "f" is actually a directory or not.
        return self._matcher.match_relative(f, True)