code: function(items) {
          var selectivity = this.selectivity;
          return items
              .map(function(item) {
                  var result = selectivity.template(item.id ? 'resultItem' : 'resultLabel', item);
                  if (item.children) {
                      result += selectivity.template('resultChildren', {
                          childrenHtml: this.renderItems(item.children)
                      });
                  }
                  return result;
              }, this)
              .join('');
      }
docs: Renders an array of result items.
  
  @param items Array of result items.
  
  @return HTML-formatted string to display the result items.