code: def _send_remote(self, url, data, headers=None, callback=None):
          
          if headers is None:
              headers = {}
  
          return AsyncHTTPClient().fetch(
              url, callback, method="POST", body=data, headers=headers,
              validate_cert=self.validate_cert
          )
docs: Initialise a Tornado AsyncClient and send the request to the sentry
          server. If the callback is a callable, it will be called with the
          response.