docs: function preparePages(output) {
      var book = output.getBook();
      var logger = book.getLogger();
  
      if (book.isMultilingual()) {
          return Promise(output);
      }
  
      return Parse.parsePagesList(book)
      .then(function(pages) {
          logger.info.ln('found', pages.size, 'pages');
  
          return output.set('pages', pages);
      });
  }