code: def warn(self, fmt, **args):
      from _pytest.warnings import _issue_warning_captured
      from _pytest.warning_types import PytestCacheWarning
  
      _issue_warning_captured(
          PytestCacheWarning(fmt.format(**args) if args else fmt),
          self._config.hook,
          stacklevel=3,
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import json
  import os
  from collections import OrderedDict
  import attr
  import py
  import six
  import pytest
  from .compat import _PY2
  from .pathlib import Path
  from .pathlib import resolve_from_str
  from .pathlib import rm_rf
label_desc: Use image node_id 3 for calling the Cache obj's underlying member method code with example usage: obj.warn(fmt) without return types