class_docstr: Adds the checked sentence to the end of the text.
  
  But only a single time.
class_docstr_tok: ["Adds","the","checked","sentence","to","the","end","of","the","text",".","But","only","a","single","time","."]
code: def checked_sentence_kword(self):
      return "checked_sentence"
  
imports: from parlai.core.mutators import register_mutator, MessageMutator, ManyEpisodeMutator
  from parlai.core.message import Message
  import parlai.tasks.wizard_of_internet.constants
  import random
label_desc: Use image node_id 1 for calling the AddCheckedSentence obj's underlying member method code with example usage: obj.checked_sentence_kword() and returns: str