code: def _terminate_conn(self, reason: str) -> None:
      if self._conn is not None:
          try:
              self._conn.terminate(reason)
          except Exception:
              pass
          self._conn = None
  
file_path: nni/nni/runtime/command_channel/websocket/channel.py
imports: from __future__ import annotations
  import logging
  import time
  from ..base import Command, CommandChannel
  from .connection import WsConnection
label_desc: Use image node_id 8 for calling the WsChannelClient obj's underlying member method code with example usage: obj._terminate_conn(reason) without return types