code: def update_group_dampening(self, group_id, dampening_id, dampening):
          
          data = self._serialize_object(dampening)
          url = self._service_url(['triggers', 'groups', group_id, 'dampenings', dampening_id])
          return Dampening(self._put(url, data))
docs: Update an existing group dampening
  
          :param group_id: Group Trigger id attached to dampening
          :param dampening_id: id of the dampening to be updated
          :return: Group Dampening created