code: def poll(self, scraper_config, headers=None):
          
          endpoint = scraper_config.get('prometheus_url')
  
          # Should we send a service check for when we make a request
          health_service_check = scraper_config['health_service_check']
          service_check_name = '{}{}'.format(scraper_config['namespace'], '.prometheus.health')
          service_check_tags = ['endpoint:{}'.format(endpoint)]
          service_check_tags.extend(scraper_config['custom_tags'])
  
          try:
              response = self.send_request(endpoint, scraper_config, headers)
          except requests.exceptions.SSLError:
              self.log.error("Invalid SSL settings for requesting {} endpoint".format(endpoint))
              raise
          except IOError:
              if health_service_check:
                  self.service_check(service_check_name, AgentCheck.CRITICAL, tags=service_check_tags)
              raise
          try:
              response.raise_for_status()
              if health_service_check:
                  self.service_check(service_check_name, AgentCheck.OK, tags=service_check_tags)
              return response
          except requests.HTTPError:
              response.close()
              if health_service_check:
                  self.service_check(service_check_name, AgentCheck.CRITICAL, tags=service_check_tags)
              raise
docs: Custom headers can be added to the default headers.
  
          Returns a valid requests.Response, raise requests.HTTPError if the status code of the requests.Response
          isn't valid - see response.raise_for_status()
  
          The caller needs to close the requests.Response
  
          :param endpoint: string url endpoint
          :param headers: extra headers
          :return: requests.Response