docstr: Get the datafile path.
  
  Useful for subclassed teachers.
docstr_tok: ["Get","the","datafile","path",".","Useful","for","subclassed","teachers","."]
code: def _get_datafile(self, opt) -> str:
      """
      Get the datafile path.
  
      Useful for subclassed teachers.
      """
      base_datatype = self._get_base_datatype(opt)
      return os.path.join(
          opt["datapath"],
          "empatheticdialogues",
          "empatheticdialogues",
          base_datatype + ".csv",
      )
  
imports: import os
  from typing import List, Optional
  import parlai.utils.logging
  from parlai.utils.io import PathManager
  from parlai.core.message import Message
  from parlai.core.params import ParlaiParser
  from parlai.core.opt import Opt
  from parlai.core.teachers import DialogTeacher
  from .build import build
label_desc: Use image node_id 4 for calling the EmpatheticDialoguesTeacher obj's underlying member method code with example usage: obj._get_datafile(opt) and returns: os