code: def close(self) -> None:
      thread = None
      with self.lock:
          self._in_shutdown = True
          # Notify blocking operations to fail.
          self.cv.notify_all()
          # Add sentinel to terminate streaming RPC.
          if self.request_queue is not None:
              # Intentional shutdown, tell server it can clean up the
              # connection immediately and ignore the reconnect grace period.
              cleanup_request = ray_client_pb2.DataRequest(
                  connection_cleanup=ray_client_pb2.ConnectionCleanupRequest()
              )
              self.request_queue.put(cleanup_request)
              self.request_queue.put(None)
          if self.data_thread is not None:
              thread = self.data_thread
      # Wait until streaming RPCs are done.
      if thread is not None:
          thread.join()
  
imports: import math
  import logging
  import queue
  import threading
  import warnings
  import grpc
  from collections import OrderedDict
  from typing import Any, Callable, Dict, TYPE_CHECKING, Optional, Union
  import ray.core.generated.ray_client_pb2
  import ray.core.generated.ray_client_pb2_grpc
  from ray.util.client.common import INT32_MAX, OBJECT_TRANSFER_CHUNK_SIZE, OBJECT_TRANSFER_WARNING_SIZE
  from ray.util.debug import log_once
label_desc: Use image node_id 12 for calling the DataClient obj's underlying member method code with example usage: obj.close() without return types