function expand( duration ) {
      if ( _isExpanded() || _isExpanding() ) {
        return this;
      }

      duration = duration || _calculateExpandDuration( _contentHeight );

      _setStateTo( EXPANDING );
      this.dispatchEvent( 'beginExpand', { target: _that } );
      _setMaxHeight();
      _transitionHeight( _expandComplete, duration );
      return this;
    }
/**
     * @param {number} duration
     *   The duration of the sliding animation in milliseconds.
     * @returns {Object} The Expandable instance.
     */
@param {number} duration
The duration of the sliding animation in milliseconds.
@returns {Object} The Expandable instance.
@param { number } duration The duration of the sliding animation in milliseconds . @returns { Object } The Expandable instance .
function expand( duration ) {
      if ( _isExpanded() || _isExpanding() ) {
        return this;
      }
      duration = duration || _calculateExpandDuration( _contentHeight );
      _setStateTo( EXPANDING );
      this.dispatchEvent( 'beginExpand', { target: _that } );
      _setMaxHeight();
      _transitionHeight( _expandComplete, duration );
      return this;
    }
function expand ( duration ) { if ( _isExpanded ( ) || _isExpanding ( ) ) { return this ; } duration = duration || _calculateExpandDuration ( _contentHeight ) ; _setStateTo ( EXPANDING ) ; this . dispatchEvent ( 'beginExpand' , { target : _that } ) ; _setMaxHeight ( ) ; _transitionHeight ( _expandComplete , duration ) ; return this ; }
@param {number} duration
   The duration of the sliding animation in milliseconds.
@param { number } duration The duration of the sliding animation in milliseconds .