public static void PrintBooksByAuthorAndTotalPrice(Library library)
        {

            foreach (var book in library.Books
                .GroupBy(b => b.Autor)
                .OrderByDescending(x => x.Sum(p => p.Price))
                .ThenBy(k => k.Key))
            {
                Console.WriteLine($"{book.Key} -> {book.Sum(p => p.Price):f2}");
            }
        }