code: def __init__(self, mailbox: Optional[mailbox.Mailbox] = None) -> None:
      self._mailbox = mailbox
      self._pending_reqs = {}
      self._lock = threading.Lock()
  
      self._join_event = threading.Event()
      self._thread = threading.Thread(target=self.message_loop)
      self._thread.name = "MsgRouterThr"
      self._thread.daemon = True
      self._thread.start()
  
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 1 to create a new MessageRouter object  with example: obj = MessageRouter(mailbox)