code: function encodeBookWithPage(book, page) {
      var file = page.getFile();
  
      var result = encodeBook(book);
      result.page = encodePage(page, book.getSummary());
      result.file = encodeFile(file);
  
      return result;
  }
docs: Return a JSON representation of a book with a specific file
  
  @param {Book} output
  @param {Page} page
  @return {Object}