code: function(color, alpha){
        var args;
        if (2 == arguments.length) {
          var c = parse(color.trim());
          args = [c.r, c.g, c.b, alpha];
        } else {
          args = [].slice.call(arguments);
        }
  
        return 'rgba(' + args.join(', ') + ')';
      }
docs: Converts RGBA(color, alpha) to the corrosponding RGBA(r, g, b, a) equivalent.
  
  background: rgba(#eee, .5)
  background: rgba(white, .2)