Go 言語を使用して、訪問調理システムの食器在庫管理モジュールを作成するにはどうすればよいですか?

type Dish struct {
    ID       int
    Name     string
    Quantity int
}

var dishes []Dish

func addDish(name string, quantity int) {
    dish := Dish{
        ID:       len(dishes) + 1,
        Name:     name,
        Quantity: quantity,
    }
    dishes = append(dishes, dish)
}

func getDishByID(id int) *Dish {
    for i := range dishes {
        if dishes[i].ID == id {
            return &dishes[i]
        }
    }
    return nil
}

func updateDishQuantity(id, quantity int) {
    dish := getDishByID(id)
    if dish != nil {
        dish.Quantity = quantity
    }
}

func deleteDish(id int) {
    for i := range dishes {
        if dishes[i].ID == id {
            dishes = append(dishes[:i], dishes[i+1:]...)
            break
        }
    }
}

func calculateTotalQuantity() int {
    var totalQuantity int
    for i := range dishes {
        totalQuantity += dishes[i].Quantity
    }
    return totalQuantity
}