class_docstr: This Teacher is responsible for performing the task of Dialogue State Tracking.
  
  It can be used to evaluate LM on JGA (Joint Goal Accuracy) metric (as shown in
  [SimpleTOD](https://arxiv.org/abs/2005.00796) and
  [Soloist](https://arxiv.org/abs/2005.05298)).
class_docstr_tok: ["This","Teacher","is","responsible","for","performing","the","task","of","Dialogue","State","Tracking",".","It","can","be","used","to","evaluate","LM","on","JGA","(","Joint","Goal","Accuracy",")","metric","(","as","shown","in","[","SimpleTOD","]","(","https",":","\/\/arxiv.org\/abs\/2005.00796",")","and","[","Soloist","]","(","https",":","\/\/arxiv.org\/abs\/2005.05298",")",")","."]
code: def _load_data(self, fold):
      dataset_fold = "dev" if fold == "valid" else fold
      fold_path = os.path.join(self.dpath, dataset_fold)
      dialogs = []
      for file_id in range(1, fold_size(dataset_fold) + 1):
          filename = os.path.join(
              fold_path, f"dialogues_{file_id:03d}.json"
          )
          with PathManager.open(filename, "r") as f:
              dialogs += json.load(f)
      return dialogs
  
imports: import copy
  import json
  import os
  from typing import Optional
  import numpy
  import pandas
  import parlai.core.tod.tod_agents
  import parlai.core.tod.tod_core
  import parlai.tasks.multiwoz_v22.build
  from parlai.core.message import Message
  from parlai.core.metrics import AverageMetric
  from parlai.core.opt import Opt
  from parlai.core.params import ParlaiParser
  from parlai.utils.data import DatatypeHelper
  from parlai.utils.io import PathManager
  from parlai.utils.testing import is_this_circleci
label_desc: Use image node_id 2 for calling the MultiWOZv22DSTTeacher obj's underlying member method code with example usage: obj._load_data(fold) and returns: dialogs