code: def _setup_data(self, fold):
      self.data = []
      fpath = os.path.join(
          self.opt["datapath"], "dailydialog", fold + ".json"
      )
      with PathManager.open(fpath) as f:
          for line in f:
              self.data.append(json.loads(line))
  
imports: import os
  import json
  from parlai.core.message import Message
  from parlai.core.teachers import FixedDialogTeacher
  from parlai.utils.io import PathManager
  from .build import build
label_desc: Use image node_id 4 for calling the Convai2Teacher obj's underlying member method code with example usage: obj._setup_data(fold) without return types