static void Main(string[] args)
{
Cart exo = new Cart("exo");
Product app1 = new Product("apple");
Product app2 = new Product("apple");
Product or1 = new Product("orange");
Product or2 = new Product("orange");
Product or3 = new Product("orange");
exo.content.Add(app1);
exo.content.Add(app2);
exo.content.Add(or1);
exo.content.Add(or2);
exo.content.Add(or3);
double cost = exo.Cost();
double final = exo.promo(cost);
Console.WriteLine("The cost of your shopping cart is : " + final);
Console.ReadLine();
}