code: function(attr, val) {
          var attrConfig = Y_Node.ATTRS[attr];
  
          if (this._setAttr) { // use Attribute imple
              this._setAttr.apply(this, arguments);
          } else { // use setters inline
              if (attrConfig && attrConfig.setter) {
                  attrConfig.setter.call(this, val);
              } else if (Y_Node.re_aria.test(attr)) { // special case Aria
                  this._node.setAttribute(attr, val);
              } else {
                  Y_Node.DEFAULT_SETTER.apply(this, arguments);
              }
          }
  
          return this;
      }
docs: Sets an attribute on the Node instance.
  Unless pre-configured (via Node.ATTRS), set hands
  off to the underlying DOM node.  Only valid
  attributes/properties for the node will be set.
  To set custom attributes use setAttribute.
  @method set
  @param {String} attr The attribute to be set.
  @param {any} val The value to set the attribute to.
  @chainable