code: function (kbItem) {
              var element = kbItem.element[0];
              var items = this._element.querySelectorAll('[kb-item]');
              for (var i = 0; i < items.length; i++) {
                  var el = items.item(i);
                  if (el === element) {
                      var siblings = {};
                      if (i !== 0) {
                          siblings.previous = angular.element(items.item(i - 1)).controller('kbItem');
                      }
                      if (i < items.length - 1) {
                          siblings.next = angular.element(items.item(i + 1)).controller('kbItem');
                      }
                      return siblings;
                  }
              }
              return {};
          }
docs: Returns the element, controller and models from the current, prevous and next item.
  
  @param {KbItemController} kbItem
  @returns {Object} with up to 2 KbItemControllers: previous and next.