static void Main(string[] args)
{
OrderService os = new OrderService();
Order order1 = new Order("A1");
OrderDetails details1 = new OrderDetails("b1", "aaa", 1, 20);
OrderDetails details2 = new OrderDetails("b2", "bbb", 2, 25);
order1.AddDetails(details1);
order1.AddDetails(details2);
Order order2 = new Order("A2");
OrderDetails details3 = new OrderDetails("c1", "ccc", 5, 50);
OrderDetails details4 = new OrderDetails("c2", "ddd", 8, 8);
order2.AddDetails(details3);
order2.AddDetails(details4);
os.orders.Add(order1);
os.orders.Add(order2);
order1.DetailList[0].ChangeCustomer("eee");
os.FindOrderWithID("A2");
os.FindOrderWithCustomer("eee");
os.FindOrderWithName("c2");
os.DeleteOrder(order2);
os.FindOrderWithName("c1");
}