code: def get_data_for_fold(self, fold):
      extrinsic_step = self.opt.get("extrinsic_step", False)
      suffix = self.fold
      if self.fold == "valid":
          suffix = "dev"
      filename = os.path.join(
          self.opt["datafile"], f"eqasc_{suffix}_grc.json"
      )
  
      json_data = json.load(PathManager.open(filename))
  
      if len(json_data) == 0:
          return
  
      data = []
      for example in json_data:
          question = example["question"]["stem"].strip()
          f1 = example["fact1"]
          f2 = example["fact2"]
          steps = [f1, f2]
          answer = example["combinedfact"]
          m = {
              "question": question,
              "answer": answer,
              "steps": steps,
          }
          if not extrinsic_step:
              yield m
          else:
              data.append(m)
  
      if extrinsic_step:
          for line in data:
              rand_steps = self.eqasc_random.choice(data)["steps"]
              random_step = self.eqasc_random.choice(rand_steps)
              yield {
                  "question": line["question"],
                  "answer": line["answer"],
                  "steps": line["steps"],
                  "extrinsic_step": random_step,
              }
  
file_path: ParlAI/parlai/tasks/eqasc/agents.py
imports: import json
  import os
  from parlai.utils.data import DatatypeHelper
  from .build import build
  from parlai.core.opt import Opt
  from parlai.core.params import ParlaiParser
  from parlai.utils.io import PathManager
  from typing import Optional
  from tasks.reasoning.agents import StepByStepReasoningTeacher
  import random
label_desc: Use image node_id 3 for calling the EqascStepByStepReasoningTeacher obj's underlying member method code with example usage: obj.get_data_for_fold(fold) without return types