public void RestoreFromUndo(Memento memento)
{
_title = memento.Title;
_author = memento.Author;
_isbn = memento.ISBN;
_lastEdited = memento.LastEdited;
}
private static void RestoreBook(Book book, Memento memento)
{
if (memento != null && book != null)
{
book.RestoreFromUndo(memento);
}
}