code: def load_module(self, path, changed_time, parser=None):
          
          if settings.use_filesystem_cache == False:
              return None
          
          try:
              pickle_changed_time = self._index[path]
          except KeyError:
              return None
  
          if (changed_time is not None and
              pickle_changed_time < changed_time):
              # the pickle file is outdated
              return None
  
          target_path = self._get_hashed_path(path)
          with open(target_path, 'rb') as f:
              try:
                  gc.disable()
                  cache_module = pickle.load(f)
                  if parser is not None:
                      for mod in cache_module:
                          mod.unpickle(parser)
              finally:
                  gc.enable()
  
          debug.dbg('pickle loaded: %s', path)
          return cache_module
docs: Attempts to load the specified module from a serialized, cached
          version. If that fails, the method returns none.