code: function(node, att, val, style) {
          style = style || node.style;
          var CUSTOM_STYLES = Y_DOM.CUSTOM_STYLES,
              current;
  
          if (style) {
              if (val === null || val === '') { // normalize unsetting
                  val = '';
              } else if (!isNaN(new Number(val)) && re_unit.test(att)) { // number values may need a unit
                  val += Y_DOM.DEFAULT_UNIT;
              }
  
              if (att in CUSTOM_STYLES) {
                  if (CUSTOM_STYLES[att].set) {
                      CUSTOM_STYLES[att].set(node, val, style);
                      return; // NOTE: return
                  } else if (typeof CUSTOM_STYLES[att] === 'string') {
                      att = CUSTOM_STYLES[att];
                  }
              }
              style[att] = val; 
          }
      }
docs: Sets a style property for a given element.
  @method setStyle
  @param {HTMLElement} An HTMLElement to apply the style to.
  @param {String} att The style property to set.
  @param {String|Number} val The value.