code: def _load_token_cache(self):
          'Reads the local fs cache for pre-authorized access tokens'
          try:
              logging.debug('About to read from local file cache file %s',
                            self.token_cache_file)
              with open(self.token_cache_file, 'rb') as f:
                  fs_cached = cPickle.load(f)
                  if self._check_token_cache_type(fs_cached):
                      logging.debug('Loaded from file system: %s', fs_cached)
                      return fs_cached
                  else:
                      logging.warn('Found unexpected value in cache. %s',
                                   fs_cached)
                      return None
          except IOError:
              logging.debug(
                  'Did not find file: %s on the file system.',
                  self.token_cache_file)
              return None
          except:
              logging.info(
                  'Encountered exception loading from the file system.',
                  exc_info=True)
              return Nonf _load_token_cache(self):
          'Reads the local fs cache for pre-authorized access tokens'
          try:
              logging.debug('About to read from local file cache file %s',
                            self.token_cache_file)
              with open(self.token_cache_file, 'rb') as f:
                  fs_cached = cPickle.load(f)
                  if self._check_token_cache_type(fs_cached):
                      logging.debug('Loaded from file system: %s', fs_cached)
                      return fs_cached
                  else:
                      logging.warn('Found unexpected value in cache. %s',
                                   fs_cached)
                      return None
          except IOError:
              logging.debug(
                  'Did not find file: %s on the file system.',
                  self.token_cache_file)
              return None
          except:
              logging.info(
                  'Encountered exception loading from the file system.',
                  exc_info=True)
              return None
docs: Reads the local fs cache for pre-authorized access tokens