code: def get_data_for_fold(self, fold):
      with PathManager.open(self.opt["datafile"]) as f:
          data = f.readlines()
  
      for line in data:
          problem = json.loads(line)
          question = problem["question"]
          answer = problem["correct"]
          #  A -> 0; B -> 1; C -> 2; D -> 3; E -> 4
          answer_idx = ord(answer) - 65
          options = problem["options"]
          rationale = problem["rationale"]
          steps = rationale.split("\n")
          yield {
              "question": question,
              "steps": steps,
              "answer_idx": answer_idx,
              "answer_choices": options,
          }
  
imports: import random
  from typing import Optional
  from parlai.tasks.reasoning.agents import MWPStepsReasoningTeacher
  from parlai.tasks.reasoning.base import AbstractQuestionAnswer, AbstractReason, AbstractReasoningTeacher
  from parlai.tasks.reasoning.question_answer import MultipleChoiceQuestionAnswer
  from parlai.tasks.reasoning.reason_types.step_by_step import StepByStepReason
  from parlai.core.opt import Opt
  from parlai.core.params import ParlaiParser
  from parlai.core.teachers import DialogTeacher
  from parlai.utils.io import PathManager
  from parlai.tasks.aqua.build import build
  import os
  import copy
  import json
label_desc: Use image node_id 5 for calling the AQuAReasoningTeacher obj's underlying member method code with example usage: obj.get_data_for_fold(fold) without return types