code: func (s *TasksCancelService) ParentTaskIdFromNodeAndId(nodeId string, id int64) *TasksCancelService {
  	if id != -1 {
  		s.parentTaskId = fmt.Sprintf("%s:%d", nodeId, id)
  	}
  	return s
  }
docs: // ParentTaskIdFromNodeAndId specifies to cancel tasks with specified parent task id.