class_docstr: Index teacher where the labels are the sentences the contain the true answer.
  
  Some punctuation may be removed from the context and the answer for tokenization
  purposes.
class_docstr_tok: ["Index","teacher","where","the","labels","are","the","sentences","the","contain","the","true","answer",".","Some","punctuation","may","be","removed","from","the","context","and","the","answer","for","tokenization","purposes","."]
code: def get(self, episode_idx, entry_idx=None):
      article_idx, paragraph_idx, qa_idx = self.examples[episode_idx]
      article = self.squad[article_idx]
      paragraph = article["paragraphs"][paragraph_idx]
      qa = paragraph["qas"][qa_idx]
      context = paragraph["context"]
      question = qa["question"]
  
      answers = [""]
      if not qa["is_impossible"]:
          answers = [a["text"] for a in qa["answers"]]
  
      # remove '.', '?', '!' from answers for proper sentence
      # tokenization
      edited_answers = []
      for answer in answers:
          new_answer = (
              answer.replace(".", "").replace("?", "").replace("!", "")
          )
          context = context.replace(answer, new_answer)
          edited_answers.append(new_answer)
  
      edited_sentences = self.sent_tok.tokenize(context)
  
      labels = []
      label_starts = []
      for sentence in edited_sentences:
          for answer in edited_answers:
              if answer in sentence and sentence not in labels:
                  labels.append(sentence)
                  label_starts.append(context.index(sentence))
                  break
  
      plausible = []
      if qa["is_impossible"]:
          plausible = qa["plausible_answers"]
          labels = [self.opt["impossible_answer_string"]]
  
      action = {
          "id": "squad",
          "text": context + "\n" + question,
          "labels": labels,
          "plausible_answers": plausible,
          "episode_done": True,
          "answer_starts": label_starts,
      }
      return action
  
imports: from typing import Optional
  from parlai.core.params import ParlaiParser
  from parlai.core.opt import Opt
  from parlai.core.teachers import FixedDialogTeacher, DialogTeacher
  from parlai.utils.io import PathManager
  from .build import build
  import json
  import os
label_desc: Use image node_id 2 for calling the SentenceIndexEditTeacher obj's underlying member method code with example usage: obj.get(episode_idx, entry_idx) and returns: action