public Pizza createPizza(string type)
        {
            Pizza pizza = null;

            if (type=="CheesePizza")
            {
                pizza = new CheesePizza();
            }
            else if (type == "ClamPizza")
            {
                pizza = new ClamPizza();
            }
            return pizza;
        }
        public Pizza createPizza(string type)
        {
            Pizza pizza = null;

            if (type == "CheesePizza")
            {
                pizza = new CheesePizza();
            }
            else if (type == "ClamPizza")
            {
                pizza = new ClamPizza();
            }
            return(pizza);
        }