code: async def probeUrl(self, url, response_headers=None):
      
      self.logger.debug("Probing URL '%s'..." % (url))
      headers = {}
      self.updateHttpHeaders(headers)
      resp_headers = {}
      resp_ok = await self.http.isReachable(url,
                                            headers=headers,
                                            response_headers=resp_headers,
                                            cache=__class__.probe_cache)
  
      if response_headers is not None:
        response_headers.update(resp_headers)
  
      return resp_ok
docs: Probe URL reachability from cache or HEAD request.