code: def index():
      
      classes = []
      with app.app_context():
          classes = set(current_app.class_references.values())
      if _get_acceptable_response_type() == JSON:
          meta_data = {}
          for cls in classes:
              meta_data[cls.endpoint()] = {
                  'link': '/' + cls.endpoint(),
                  'meta': '/' + cls.endpoint() + '/meta'
                  }
          return jsonify(meta_data)
      else:
          return render_template('index.html', classes=classes)
docs: Return information about each type of resource and how it can be
      accessed.