private void DemoProxy()
        {
            IDemoProxy proxy = new RealProxy();

            proxy.InsertString("Peter");
            proxy.InsertString("Anders");
            proxy.InsertString("Vibeke");
            proxy.InsertString("Michael C");

            foreach (string s in proxy.GetAll())
            {
                Console.WriteLine(s);
            }

            Console.WriteLine("    AFTER PROXY ");
            IDemoProxy proxy2 = new ProxyClass("SWC");

            proxy2.InsertString("Peter");
            proxy2.InsertString("Anders");

            foreach (string s in proxy2.GetAll())
            {
                Console.WriteLine(s);
            }
        }