code: function() {
              YUD.batch(this._panels, function(e) {
                  var elContent = this.firstChild.nextSibling;
                  if(elContent) { 
                      YUD.removeClass(e.firstChild, this.CLASSES.ACTIVE);
                      YUD.addClass(elContent, this.CLASSES.HIDDEN);
                      this._setARIA(elContent, 'aria-hidden', 'true');
                  }
              }, this);
          }
docs: Closes all panels
  @method _collapseAccordion
  @private