code: function(current, $scope) {
              var $selfRef = this;
  
              var selectables = $selfRef._tabItems($scope);
              var nextIndex = 0;
              if ($(current).length === 1){
                  var currentIndex = selectables.index(current);
                  if (currentIndex + 1 < selectables.length) {
                      nextIndex = currentIndex + 1;
                  }
              }
              return selectables.eq(nextIndex);
          }
docs: Find the next tabbabale item after given element