code: func (r *GormWorkItemTypeRepository) AddChildTypes(ctx context.Context, parentTypeID uuid.UUID, childTypeIDs []uuid.UUID) error {
  	defer goa.MeasureSince([]string{"goa", "db", "workitemtype", "add_child_types"}, time.Now())
  	if len(childTypeIDs) <= 0 {
  		return nil
  	}
  	// Create entries for each child in the type list
  	for idx, ID := range childTypeIDs {
  		childType := ChildType{
  			ParentWorkItemTypeID: parentTypeID,
  			ChildWorkItemTypeID:  ID,
  			Position:             idx,
  		}
  		db := r.db.Create(&childType)
  		if db.Error != nil {
  			return errors.NewInternalError(ctx, db.Error)
  		}
  	}
  	ClearGlobalWorkItemTypeCache()
  	return nil
  
  }
docs: // AddChildTypes adds the given child work item types to the parent work item
  // type.