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):
        # Some information is lost in the superclass's constructor, so we
        # can not accurately create the matching function for the subdirectory
        # from the inputs. Instead, we override matchfn() and visitdir() to
        # call the original matcher with the subdirectory path prepended.
        return self._matcher.matchfn(self._path + "/" + f)