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
docstr: Initialize the connection
docstr_tok: ["Initialize","the","connection"]
code: def _init_conn(self, message):
      """Initialize the connection"""
      if len(message) != 4:
          logger.warning("Invalid connection from %s", self.name())
          self.close()
      magic = struct.unpack("<i", message)[0]
      if magic != RPC_TRACKER_MAGIC:
          logger.warning("Invalid magic from %s", self.name())
          self.close()
      self.write_message(
          struct.pack("<i", RPC_TRACKER_MAGIC), binary=True
      )
      self._init_req_nbytes = 0
  
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 4 for calling the TCPEventHandler obj's underlying member method code with example usage: obj._init_conn(message) without return types