code: def create_webhook(self, events, url, payload_format):
          
          body = {
              "Events": events,
              "Url": url,
              "PayloadFormat": payload_format}
          response = self._post(self.uri_for("webhooks"), json.dumps(body))
          return json_to_py(response)
docs: Creates a new webhook for the specified events (an array of strings). 
          Valid events are "Subscribe", "Deactivate", and "Update".
          Valid payload formats are "json", and "xml".