docs: def _http_resp_rate_limited(response):
          """Extract the ``Retry-After`` header value if the request was rate
          limited and return a future to sleep for the specified duration.
  
          :param tornado.httpclient.HTTPResponse response: The response
          :rtype: tornado.concurrent.Future
  
          """
          parsed = parse.urlparse(response.request.url)
          duration = int(response.headers.get('Retry-After', 3))
          LOGGER.warning('Rate Limited by %s, retrying in %i seconds',
                         parsed.netloc, duration)
          return asyncio.sleep(duration)