code: def _unsubscribe_request(self, channels):
      req = gcs_service_pb2.GcsSubscriberCommandBatchRequest(
          subscriber_id=self._subscriber_id,
          sender_id=self._worker_id,
          commands=[],
      )
      for channel in channels:
          req.commands.append(
              pubsub_pb2.Command(
                  channel_type=channel, unsubscribe_message={}
              )
          )
      return req
  
imports: import asyncio
  from collections import deque
  import logging
  import random
  from typing import Tuple, List
  import grpc
  from ray._private.utils import get_or_create_event_loop
  import ray._private.gcs_utils
  import ray._private.logging_utils
  from ray.core.generated.gcs_pb2 import ErrorTableData
  from ray.core.generated import dependency_pb2
  from ray.core.generated import gcs_service_pb2_grpc
  from ray.core.generated import gcs_service_pb2
  from ray.core.generated import common_pb2
  from ray.core.generated import pubsub_pb2
label_desc: Use image node_id 5 for calling the _SubscriberBase obj's underlying member method code with example usage: obj._unsubscribe_request(channels) and returns: req