code: function moveFocus(dir, elements) {
          var idx = -1, navigationRoot = getNavigationRoot();
  
          elements = elements || getFocusElements(navigationRoot.getEl());
  
          for (var i = 0; i < elements.length; i++) {
            if (elements[i] === focusedElement) {
              idx = i;
            }
          }
  
          idx += dir;
          navigationRoot.lastAriaIndex = moveFocusToIndex(idx, elements);
        }
docs: Moves the focus forwards or backwards.
  
  @private
  @param {Number} dir Direction to move in positive means forward, negative means backwards.
  @param {Array} elements Optional array of elements to move within defaults to the current navigation roots elements.