code: def shutdown(self):
      if self.chat_done:
          self.opt["run_statistics"][
              f"{self.bots[0].worker_id}:{self.bots[1].worker_id}"
          ] += 1
          logging.info(
              "Runs completed per model: "
              + ", ".join(
                  f"{model}: {count:d}"
                  for model, count in self.opt["run_statistics"].items()
              )
          )
  
      self.agent.shutdown()
  
imports: import random
  import parlai.utils.logging
  from typing import Any, Dict, Optional
  from parlai.core.agents import create_agent_from_shared
  from parlai.core.message import Message
  from parlai.core.worlds import validate
  from parlai.crowdsourcing.tasks.model_chat.constants import ONBOARD_SUCCESS
  from parlai.crowdsourcing.tasks.model_chat.utils import Compatibility
  from parlai.crowdsourcing.tasks.model_chat.worlds import BaseModelChatWorld, ModelChatWorld, ModelChatOnboardWorld
  from parlai.crowdsourcing.utils.acceptability import AcceptabilityChecker
  from parlai.crowdsourcing.utils.mturk import get_mturk_id_from_mephisto_wrapper
  from parlai.crowdsourcing.tasks.pairwise_per_turn_eval.bot_agent import PerTurnEvalTurkLikeAgent
label_desc: Use image node_id 6 for calling the PerTurnEvalWorld obj's underlying member method code with example usage: obj.shutdown() without return types