class_docstr: Passthrough world to spawn task worlds of only one type.
  
  Demos of more advanced overworld functionality exist in the overworld demo
code: def parley(self):
      self.episodeDone = True
      return "default"
  
file_path: ParlAI/parlai/chat_service/services/messenger/worlds.py
imports: from parlai.core.worlds import World
label_desc: Use image node_id 4 for calling the SimpleMessengerOverworld obj's underlying member method code with example usage: obj.parley() and returns: str