code: function(o) {
        if (typeof o == 'number' || o instanceof SVG.Number) {
          o = {
            offset:  arguments[0]
          , color:   arguments[1]
          , opacity: arguments[2]
          }
        }
  
        // set attributes
        if (o.opacity != null) this.attr('stop-opacity', o.opacity)
        if (o.color   != null) this.attr('stop-color', o.color)
        if (o.offset  != null) this.attr('offset', new SVG.Number(o.offset))
  
        return this
      }
docs: add color stops