code: def _load_personas(opt):
      print("[ loading personas.. ]")
      # Create ConvAI2 data so we can assign personas.
      convai2_opt = opt.copy()
      convai2_opt["task"] = "convai2:both"
      if convai2_opt["datatype"].startswith("train"):
          convai2_opt["datatype"] = "train:evalmode"
      convai2_opt["interactive_task"] = False
      convai2_opt["selfchat_task"] = False
      convai2_agent = FixedResponseAgent({"fixed_response": None})
      convai2_world = create_task(convai2_opt, convai2_agent)
      personas = set()
      while not convai2_world.epoch_done():
          convai2_world.parley()
          msg = convai2_world.get_acts()[0]
          # Find a new episode
          if (
              msg.get("episode_done", False)
              and not convai2_world.epoch_done()
          ):
              convai2_world.parley()
              msg = convai2_world.get_acts()[0]
              txt = msg.get("text", "").split("\n")
              a1_persona = []
              a2_persona = []
              for t in txt:
                  if t.startswith("partner's persona:"):
                      a1_persona.append(
                          t.replace(
                              "partner's persona:", "your persona:"
                          )
                      )
                  if t.startswith("your persona:"):
                      a2_persona.append(t)
              personas.add("\n".join(a1_persona))
              personas.add("\n".join(a2_persona))
      print("[ loaded " + str(len(personas)) + " personas ]")
      return list(personas)
  
imports: from typing import Optional
  from parlai.core.params import ParlaiParser
  from parlai.core.opt import Opt
  from parlai.core.worlds import create_task
  from parlai.agents.fixed_response.fixed_response import FixedResponseAgent
  from parlai.tasks.self_chat.worlds import SelfChatWorld
  from parlai.tasks.interactive.worlds import InteractiveWorld
  import random
label_desc: Use image node_id 2 for calling a global function with example usage: _load_personas(opt) and returns: list