code: def shutdown(self) -> None:
      self.server_shutdown = True
      SocketServer.TCPServer.shutdown(self)
      self.server_close()
  
imports: import sys
  import select
  import struct
  import socketserver
  import threading
  from typing import Callable, Dict, Generic, Tuple, Type, TYPE_CHECKING, TypeVar, Union
  from pyspark.serializers import read_int, CPickleSerializer
  from pyspark.errors import PySparkRuntimeError
label_desc: Use image node_id 2 for calling the AccumulatorServer obj's underlying member method code with example usage: obj.shutdown() without return types