code: def _ensure_conn(self) -> WsConnection:
      if self._conn is None and not self._closing:
          self._conn = WsConnection(self._url)
          self._conn.connect()
          _logger.debug("Connected")
      return self._conn
  
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 6 for calling the WsChannelClient obj's underlying member method code with example usage: obj._ensure_conn() and returns: self