code: def test_word_reverse(self):
      from parlai.mutators.word_reverse import WordReverseMutator
  
      ex1, ex2, ex3, ex4 = self._apply_mutator(WordReverseMutator)
  
      # check episode done is always set correctly
      assert not ex1["episode_done"]
      assert ex2["episode_done"]
      assert not ex3["episode_done"]
      assert ex4["episode_done"]
  
      # assert correct texts
      assert ex1["text"] == "Stephen is name my Hi,"
      assert ex2["text"] == "name? your is What"
      assert ex3["text"] == "Emily. I'm Hello,"
      assert ex4["text"] == "called? you are What"
  
imports: import unittest
  from parlai.core.params import ParlaiParser
  from parlai.core.opt import Opt
  from parlai.core.teachers import create_task_agent_from_taskname
  from parlai.core.message import Message
label_desc: Use image node_id 12 for calling the TestSpecificMutators obj's underlying member method code with example usage: obj.test_word_reverse() without return types