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 _get_snapshot_status(self, snapshot_id):
        resp, body = self.get_snapshot(snapshot_id)
        status = body['status']
        # NOTE(afazekas): snapshot can reach an "error"
        # state in a "normal" lifecycle
        if (status == 'error'):
            raise exceptions.SnapshotBuildErrorException(
                snapshot_id=snapshot_id)

        return status