code: function filterSummary(paths) {
      var $summary = $('.book-summary');
  
      $summary.find('li').each(function() {
          var path = $(this).data('path');
          var st = paths == null || _.contains(paths, path);
  
          $(this).toggle(st);
          if (st) $(this).parents('li').show();
      });
  }
docs: Filter summary with a list of path