code: def skipUnlessMephisto(testfn, reason="mephisto not installed"):
      """
      Decorate a test to skip unless mephisto is installed.
      """
      return unittest.skipUnless(MEPHISTO_AVAILABLE, reason)(testfn)
  
imports: import os
  import unittest
  import contextlib
  import tempfile
  import shutil
  import io
  import signal
  from typing import Tuple, Dict, Any
  from parlai.core.opt import Opt
  import parlai.utils.logging
  from parlai.utils.io import PathManager
  from pytest_regressions.data_regression import DataRegressionFixture
label_desc: Use image node_id 11 for calling a global function with example usage: skipUnlessMephisto(testfn, reason) and returns: unittest