code: def get(self):
          
          logger.info(
              'Loading refresh_token from %s', repr(self._filename)
          )
          try:
              with open(self._filename) as f:
                  return f.read()
          except IOError as e:
              logger.info('Failed to load refresh_token: %s', e)
docs: Get cached refresh token.
  
          Returns:
              Cached refresh token, or ``None`` on failure.