code: def notify_hosts_updated(self, timestamp, update_res):
      self._send(HostsUpdatedRequest(timestamp, update_res))
  
imports: import os
  import threading
  from enum import IntFlag
  from horovod.runner.common.util import network, secret
  from horovod.runner.elastic.rendezvous import PUT_WORKER_ADDRESSES
  from horovod.runner.http.http_client import put_data_into_kvstore
label_desc: Use image node_id 2 for calling the WorkerNotificationClient obj's underlying member method code with example usage: obj.notify_hosts_updated(timestamp, update_res) without return types