code: func (r *GormWorkItemRepository) LoadHighestOrder(ctx context.Context, spaceID uuid.UUID) (float64, error) {
  	res := WorkItemStorage{}
  	db := r.db.Model(WorkItemStorage{})
  	query := fmt.Sprintf("execution_order = (SELECT max(execution_order) FROM %[1]s where space_id=?)",
  		WorkItemStorage{}.TableName(),
  	)
  	db = db.Where(query, spaceID).First(&res)
  	if db.Error != nil && !db.RecordNotFound() {
  		return 0, errors.NewInternalError(ctx, db.Error)
  	}
  	order, err := strconv.ParseFloat(fmt.Sprintf("%v", res.ExecutionOrder), 64)
  	if err != nil {
  		return 0, errors.NewInternalError(ctx, err)
  	}
  	return order, nil
  }
docs: // LoadHighestOrder returns the highest execution order in the given space