code: def tempfile(self) -> IO[Any]:
      self._tempfile = tempfile.NamedTemporaryFile(
          delete=False, **self.kwargs
      )
      self.tempfile_pool.append(self._tempfile)
      return self._tempfile
  
file_path: optuna/optuna/testing/tempfile_pool.py
imports: from __future__ import annotations
  import atexit
  import gc
  import os
  import tempfile
  from types import TracebackType
  from typing import Any
  from typing import IO
label_desc: Use image node_id 3 for calling the NamedTemporaryFilePool obj's underlying member method code with example usage: obj.tempfile() and returns: self