docs: def delete_instance_if_removed(self, port):
          """Enqueue instance delete if it's no longer in the db"""
          instance_type = self.get_instance_type(port)
          if not instance_type:
              return
          if not db_lib.instance_provisioned(port['device_id']):
              i_res = MechResource(port['device_id'], instance_type,
                                   a_const.DELETE)
              self.provision_queue.put(i_res)