code: function() {
              return $(this).each(function() {
                  var $this = $(this);
                  var expander = $this.treegrid('getSetting', 'getExpander').apply(this);
                  if (expander) {
  
                      if (!$this.treegrid('isCollapsed')) {
                          expander.removeClass($this.treegrid('getSetting', 'expanderCollapsedClass'));
                          expander.addClass($this.treegrid('getSetting', 'expanderExpandedClass'));
                      } else {
                          expander.removeClass($this.treegrid('getSetting', 'expanderExpandedClass'));
                          expander.addClass($this.treegrid('getSetting', 'expanderCollapsedClass'));
                      }
                  } else {
                      $this.treegrid('initExpander');
                      $this.treegrid('renderExpander');
                  }
              });
          }
docs: Rendering expander depends on node state
  
  @returns {Node}