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 update_snapshot_status(self, snapshot_id, status, progress):
        """Update the specified snapshot's status."""
        post_body = {
            'status': status,
            'progress': progress
        }
        post_body = json.dumps({'os-update_snapshot_status': post_body})
        url = 'snapshots/%s/action' % str(snapshot_id)
        resp, body = self.post(url, post_body)
        return resp, body