class_docstr: Base asynchronize message handler.
  
  The tracker and client follows a simple message protocol.
  The message is in form [nbytes(int32)] [json-str].
  All the information is packed in json-str
code: def on_error(self, err):
      logger.warning("%s: Error in RPC Tracker: %s", self.name(), err)
      self.close()
  
imports: import asyncio
  import heapq
  import logging
  import socket
  import threading
  import errno
  import struct
  import json
  from tvm.contrib.popen_pool import PopenWorker
  from .._ffi.base import py_str
  from .None import base
  from .base import RPC_TRACKER_MAGIC, TrackerCode
label_desc: Use image node_id 9 for calling the TCPEventHandler obj's underlying member method code with example usage: obj.on_error(err) without return types