code: def _path(exsz, task, opt):
      # Build the data if it doesn't exist.
      build(opt)
      suffix = ""
      dt = opt["datatype"].split(":")[0]
      if dt == "train":
          suffix = "trn"
      elif dt == "test":
          suffix = "tst"
      elif dt == "valid":
          suffix = "dev"
      return os.path.join(
          opt["datapath"],
          "personalized-dialog",
          "personalized-dialog-dataset",
          "{exsz}".format(exsz=exsz),
          "{tsk}-{type}.txt".format(tsk=tasks[int(task)], type=suffix),
      )
  
imports: from parlai.core.teachers import FbDeprecatedDialogTeacher, MultiTaskTeacher
  from .build import build
  import copy
  import os
label_desc: Use image node_id 1 for calling a global function with example usage: _path(exsz, task, opt) and returns: os