class_docstr: This handler will keep polling updates from the same socket until the
  server is shutdown.
code: def handle(self) -> None:
      from pyspark.accumulators import _accumulatorRegistry
  
      auth_token = self.server.auth_token  # type: ignore[attr-defined]
  
      def poll(func: Callable[[], bool]) -> None:
          while not self.server.server_shutdown:  # type: ignore[attr-defined]
              # Poll every 1 second for new data -- don't block in case of shutdown.
              r, _, _ = select.select([self.rfile], [], [], 1)
              if self.rfile in r and func():
                  break
  
      def accum_updates() -> bool:
          num_updates = read_int(self.rfile)
          for _ in range(num_updates):
              (aid, update) = pickleSer._read_with_length(self.rfile)
              _accumulatorRegistry[aid] += update
          # Write a byte in acknowledgement
          self.wfile.write(struct.pack("!b", 1))
          return False
  
      def authenticate_and_accum_updates() -> bool:
          received_token: Union[bytes, str] = self.rfile.read(
              len(auth_token)
          )
          if isinstance(received_token, bytes):
              received_token = received_token.decode("utf-8")
          if received_token == auth_token:
              accum_updates()
              # we've authenticated, we can break out of the first loop now
              return True
          else:
              raise ValueError(
                  "The value of the provided token to the AccumulatorServer is not correct."
              )
  
      # first we keep polling till we've received the authentication token
      poll(authenticate_and_accum_updates)
      # now we've authenticated, don't need to check for the token anymore
      poll(accum_updates)
  
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 1 for calling the _UpdateRequestHandler obj's underlying member method code with example usage: obj.handle() and returns: False, True