public void Promo(merchandises name)
        {
            int compt = 0;

            for (int i = 0; i < ListCourses.Count; i++)
            {
                if (compt == 0 && ListCourses[i].name == "apple")
                {
                    merchandises apple = new merchandises("apple", 0.60);
                    ListCourses.Add(apple);
                    compt++;
                }
                else
                {
                    compt = 0;
                }
            }
        }
        static void Main(string[] args)
        {
            //orange = 60;
            //apple = 25;
            merchandises apple  = new merchandises("apple", 0.60);
            merchandises orange = new merchandises("orange", 0.25);
            merchandises banana = new merchandises("banana", 0.15);
            merchandises chair  = new merchandises("orange", 25);

            List <merchandises> fruits = new List <merchandises>();

            fruits.Add(orange);
            fruits.Add(apple);
            fruits.Add(apple);
            fruits.Add(apple);
            checkout ListCourses = new checkout(fruits);

            ListCourses.Promo(apple);
            Console.WriteLine("Shopping List:");
            Console.WriteLine(ListCourses.ToString());
            Console.WriteLine($"You need to pay £{ListCourses.Sum()}");
            Console.ReadKey();
        }
 public void Add(merchandises product)
 {
     ListCourses.Add(product);
 }