code: def _read_message(self) -> Optional["pb.Result"]:
      raise NotImplementedError
  
imports: import logging
  import threading
  import uuid
  from abc import abstractmethod
  from typing import TYPE_CHECKING, Dict, Optional
  from ..lib import mailbox, tracelog
  from .message_future import MessageFuture
label_desc: Use image node_id 2 for calling the MessageRouter obj's underlying member method code with example usage: obj._read_message() without return types