static Author toDomainModel(nz.ac.auckland.bookShare.dto.Author dtoAuthor) {
   Author fullAuthor =
       new Author(dtoAuthor.getId(), dtoAuthor.getFirstName(), dtoAuthor.getLastName());
   if (dtoAuthor.getWrittenBooks().size() > 0) {
     for (long bookID : dtoAuthor.getWrittenBooks()) {
       fullAuthor.addNewWritten(new Book(bookID));
     }
   }
   return fullAuthor;
 }
 static nz.ac.auckland.bookShare.dto.Author toDto(Author author) {
   nz.ac.auckland.bookShare.dto.Author dtoAuthor =
       new nz.ac.auckland.bookShare.dto.Author(
           author.getId(), author.getFirstName(), author.getLastName());
   if (author.getWrittenBooks().size() > 0) {
     for (Book book : author.getWrittenBooks()) {
       dtoAuthor.addNewWritten(book.getId());
     }
   }
   return dtoAuthor;
 }