public void delete(String bookTitle) {
   request.delete(bookTitle);
 }
 public void delBooksAndAuthors(String firstName) {
   request.delBooksAndAuthors(firstName);
 }
 public void update(String bookTitle, String bookGenre, int yearOfPublish, double price) {
   request.update(bookTitle, bookGenre, yearOfPublish, price);
 }
 public void insertAuthor(String firstNameAuthor, String lastName) {
   request.insertAuthor(firstNameAuthor, lastName);
 }
 public void insertBook(
     String bookTitle, String bookGenre, int yearOfPublish, double price, String firstNameAuthor) {
   request.insertBook(bookTitle, bookGenre, yearOfPublish, price, firstNameAuthor);
 }
 public List<Author> showAuthors() {
   return request.showAuthors();
 }
 public List<Books> showBookByAuthor(String bookName) {
   return request.showBookByAuthor(bookName);
 }