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

def update_group_dampening(self, group_id, dampening_id, dampening):
        """
        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
        """
        data = self._serialize_object(dampening)
        url = self._service_url(['triggers', 'groups', group_id, 'dampenings', dampening_id])
        return Dampening(self._put(url, data))