code: def _format_selector_observation(
      self, knowledge_no_title, episode_done=False
  ):
      obs = {"episode_done": episode_done}
      obs["label_candidates"] = [
          x for x in knowledge_no_title.split("\n") if x
      ]
      text = self.retriever_history.get("chosen_topic", "")
      if len(self.dialogue_history) > 0:
          if len(self.dialogue_history) > 1:
              text += self.dialogue_history[-2]["text"]
          text += self.dialogue_history[-1]["text"]
      obs["text"] = text
      return obs
  
imports: from typing import Optional
  from parlai.core.params import ParlaiParser
  from parlai.core.opt import Opt
  from parlai.core.agents import Agent, create_agent, create_agent_from_shared
  from parlai.core.torch_ranker_agent import TorchRankerAgent
  from parlai.tasks.wizard_of_wikipedia.agents import TOKEN_KNOWLEDGE
  from parlai.zoo.wizard_of_wikipedia.knowledge_retriever import download
  import json
  import os
label_desc: Use image node_id 10 for calling the KnowledgeRetrieverAgent obj's underlying member method code with example usage: obj._format_selector_observation(knowledge_no_title, episode_done) and returns: obs