class_docstr: Episode-level mutators.
docstr: Abstract episode mutation.
  
  The main method to implement when implementing an EpisodeMutator.
  
  The "episode_done" field will be automatically stripped before providing
  as input, and automatically added back to the finalized episode.
  
  :param messages:
      All the messages in one episode. You may manipulate any or all of
      them, or change the ordering entirely.
  :returns:
      The new, mutated episode.
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code: def episode_mutation(self, episode: List[Message]) -> List[Message]:
      """
      Abstract episode mutation.
  
      The main method to implement when implementing an EpisodeMutator.
  
      The "episode_done" field will be automatically stripped before providing
      as input, and automatically added back to the finalized episode.
  
      :param messages:
          All the messages in one episode. You may manipulate any or all of
          them, or change the ordering entirely.
      :returns:
          The new, mutated episode.
      """
      pass
  
imports: from __future__ import annotations
  import abc
  import importlib
  import pkgutil
  from typing import Optional, Iterable, Tuple, List, Iterator, Callable, Type
  import parlai.mutators
  from parlai.core.params import ParlaiParser
  from parlai.core.opt import Opt
  from parlai.core.message import Message
label_desc: Use image node_id 1 for calling the EpisodeMutator obj's underlying member method code with example usage: obj.episode_mutation(episode) without return types