function init() {
    if ( !atomicHelpers.setInitFlag( _dom ) ) {
      return standardType.UNDEFINED;
    }

    var expandable = new Expandable( _dom );
    expandable.init();

    return this;
  }
/**
   * @returns {SecondaryNavigation|undefined} An instance,
   *   or undefined if it was already initialized.
   */
@returns {SecondaryNavigation|undefined} An instance,
or undefined if it was already initialized.
@returns { SecondaryNavigation|undefined } An instance or undefined if it was already initialized .
function init() {
    if ( !atomicHelpers.setInitFlag( _dom ) ) {
      return standardType.UNDEFINED;
    }
    var expandable = new Expandable( _dom );
    expandable.init();
    return this;
  }
function init ( ) { if ( ! atomicHelpers . setInitFlag ( _dom ) ) { return standardType . UNDEFINED ; } var expandable = new Expandable ( _dom ) ; expandable . init ( ) ; return this ; }
@returns {SecondaryNavigation|undefined} An instance,
   or undefined if it was already initialized.
@returns { SecondaryNavigation|undefined } An instance or undefined if it was already initialized .