code: def _GetPlistRootKey(self, file_entry):
      
      file_object = file_entry.GetFileObject()
  
      try:
        plist_file = plist.PlistFile()
        plist_file.Read(file_object)
  
      except IOError as exception:
        location = getattr(file_entry.path_spec, 'location', '')
        raise errors.PreProcessFail(
            'Unable to read plist file: {0:s} with error: {1!s}'.format(
                location, exception))
  
      finally:
        file_object.close()
  
      return plist_file.root_key
docs: Retrieves the root key of a plist file.
  
      Args:
        file_entry (dfvfs.FileEntry): file entry of the plist.
  
      Returns:
        dict[str, object]: plist root key.
  
      Raises:
        errors.PreProcessFail: if the preprocessing fails.