code: function (value) {
              if (!this._isValidIndex(value) || this._focusIndex == value) {
                  return;
              }
              this._focusIndex = value;
              this.indexFocused.emit(value);
              this._setTabFocus(value);
          }
docs: When the focus index is set, we must manually send focus to the correct label
  @param {?} value
  @return {?}