def insert(self, doc, synced=False):
        doc.id = self.get_next_id()
        doc.synced = synced
        try:
            self.db.docs.insert(doc)
        except Exception as e:
            raise DatabaseException(e)
        return doc
def modify(self, pmtu):
        self.pmtu = pmtu
        self._test.vapi.ip_path_mtu_update(pmtu={'nh': self.nh,
                                                 'table_id': self.table_id,
                                                 'path_mtu': self.pmtu})
        return self