/// <summary>
        /// Entry point into console application.
        /// </summary>
        private static void Main()
        {
            // Create book
            Book book = new Book("Worley", "Inside ASP.NET", 10);

            book.Display();

            // Create video
            Video video = new Video("Spielberg", "Jaws", 23, 92);

            video.Display();

            // Make video borrowable, then borrow and display
            Console.WriteLine("\nMaking video borrowable:");

            Borrowable borrowvideo = new Borrowable(video);

            borrowvideo.BorrowItem("Customer #1");
            borrowvideo.BorrowItem("Customer #2");

            borrowvideo.Display();

            // Wait for user
            Console.ReadKey();
        }
        /// <summary>
        /// Entry point into console application.
        /// </summary>
        private static void Main()
        {
            // Create book
              Book book = new Book("Worley", "Inside ASP.NET", 10);
              book.Display();

              // Create video
              Video video = new Video("Spielberg", "Jaws", 23, 92);
              video.Display();

              // Make video borrowable, then borrow and display
              Console.WriteLine("\nMaking video borrowable:");

              Borrowable borrowvideo = new Borrowable(video);
              borrowvideo.BorrowItem("Customer #1");
              borrowvideo.BorrowItem("Customer #2");

              borrowvideo.Display();

              // Wait for user
              Console.ReadKey();
        }