docstr: Override to return one or more opening messages with which to seed the self chat
  episode.
  
  The return value should be an array of strings, each string being a message in
  response to the string before it.
docstr_tok: ["Override","to","return","one","or","more","opening","messages","with","which","to","seed","the","self","chat","episode",".","The","return","value","should","be","an","array","of","strings",",","each","string","being","a","message","in","response","to","the","string","before","it","."]
code: def get_openers(self, episode_num: int) -> Optional[List[str]]:
      """
      Override to return one or more opening messages with which to seed the self chat
      episode.
  
      The return value should be an array of strings, each string being a message in
      response to the string before it.
      """
      if self._openers:
          return [random.choice(self._openers)]
      return None
  
imports: import copy
  import random
  from typing import Any, Dict, List, Optional
  from parlai.agents.fixed_response.fixed_response import FixedResponseAgent
  from parlai.core.agents import Agent
  from parlai.core.worlds import create_task, DialogPartnerWorld, validate
  from parlai.core.message import Message
label_desc: Use image node_id 5 for calling the SelfChatWorld obj's underlying member method code with example usage: obj.get_openers(episode_num) and returns: None, list