code: def _path(opt):
      build(opt)
      dt = opt["datatype"].split(":")[0]
  
      if dt == "train":
          path = os.path.join(
              opt["datapath"], "ConvAIChitChat", "train.json"
          )
      elif dt == "test":
          path = os.path.join(
              opt["datapath"], "ConvAIChitChat", "test.json"
          )
      elif dt == "valid":
          raise RuntimeError("warning: validation is not supported")
      else:
          raise RuntimeError("Not valid datatype.")
  
      return path
  
file_path: ParlAI/parlai/tasks/convai_chitchat/agents.py
imports: from .build import build
  from parlai.core.teachers import DialogTeacher
  from parlai.utils.io import PathManager
  import json
  import os
label_desc: Use image node_id 2 for calling the DefaultTeacher obj's underlying member method code with example usage: obj._path(opt) and returns: path