code: def get_data_for_fold(self, fold):
      extrinsic_step = self.opt.get("extrinsic_step", False)
  
      with PathManager.open(self.opt["datafile"]) as f:
          data = f.readlines()
  
      messages = []
      for line in data:
          problem = json.loads(line)
          question = (
              problem["question"].replace(" .", ".").replace(" ,", ",")
          )
          options = {}
          for x in problem["options"]:
              try:
                  a, b = x.split(" ) ")
              except ValueError:
                  if "(" not in x:
                      # some lines have typos and duplicate indices
                      a, c, b = x.split(" ) ")
                  else:
                      # example: B ) ( 4 ! - 1 ) * ( 5 ! - 1 ) * ( 6 ! - 1 )
                      a = x.split(" ) ")[0]
                      b = " ) ".join(x.split(" ) ")[1:])
              options[a] = b
          answer = options[problem["correct"]]
          rationale = problem["rationale"]
          steps = rationale.split("\n")
          final_steps = []
          # some steps are just dots or empty
          for step in steps:
              while len(step) > 0 and (
                  step[-1] == "." or step[-1] == " "
              ):
                  step = step[:-1]
              if len(step) > 0:
                  final_steps.append(step)
          m = {
              "question": question,
              "steps": final_steps,
              "answer": answer,
          }
          if not extrinsic_step:
              yield m
          else:
              messages.append(m)
  
      if extrinsic_step:
          for line in messages:
              rand_steps = self.aqua_random.choice(messages)["steps"]
              random_step = self.aqua_random.choice(rand_steps)
              yield {
                  "question": line["question"],
                  "answer": line["answer"],
                  "steps": line["steps"],
                  "extrinsic_step": random_step,
              }
  
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 3 for calling the AQuAStepByStepReasoningTeacher obj's underlying member method code with example usage: obj.get_data_for_fold(fold) without return types