code: def _cleanup(self):
      ret = None
      try:
          ret = super(WebSocketClientBase, self)._cleanup()
      except Exception:
          pass
      return ret
  
imports: import json
  import time
  import threading
  import six
  from ws4py.client import tornadoclient
  import tornado
  import pyalgotrade.logger
label_desc: Use image node_id 2 for calling the WebSocketClientBase obj's underlying member method code with example usage: obj._cleanup() and returns: ret