code: def _lookup_mock_fs(self, filename):
      path = filename.lstrip("/").split("/")
      curdir = self._mock_fs
      for item in path:
          if item in curdir:
              curdir = curdir[item]
          else:
              return None
      return curdir
  
imports: import stat
  import unittest
  import yaml
  from collections import namedtuple
  from unittest.mock import patch
  from parameterized import parameterized
  import __res
label_desc: Use image node_id 5 for calling the ImporterMocks obj's underlying member method code with example usage: obj._lookup_mock_fs(filename) and returns: curdir, None