private void printMenu(Iterator iterator)
 {
     while (iterator.hasNext())
     {
         MenuItem menuItem = (MenuItem)iterator.next();
         Console.WriteLine(menuItem.getName() + ", ");
         Console.WriteLine(menuItem.getPrice() + " -- ");
         Console.WriteLine(menuItem.getDescription());
     }
 }
        // Start is called before the first frame update
        void Start()
        {
            BookShelf bookShelf = new BookShelf(4);

            bookShelf.appendBook(new Book("Around the World in  Days"));
            bookShelf.appendBook(new Book("Bible"));
            bookShelf.appendBook(new Book("Ciderella"));
            bookShelf.appendBook(new Book("Daddy-Long-Legs"));
            Iterator it = bookShelf.iterator();

            while (it.hasNext())
            {
                Book book = (Book)it.next();
                Debug.Log(book.getName());
            }
        }