class index extends Paged.Handler {
  constructor(chunker, polisher, caller) {
      super(chunker, polisher, caller);
  }

  beforeParsed(content) {
    createIndex({
      content: content,
      spanClassIndex: '.book-index',
      indexElement: '#book-index',  
      alphabet: true        
    });
  }
}

Paged.registerHandlers(index);