docs: function(use3d) {
        var re = [];
  
        for (var i in this) {
          if (this.hasOwnProperty(i)) {
            // Don't use 3D transformations if the browser can't support it.
            if ((!support.transform3d) && (
              (i === 'rotateX') ||
              (i === 'rotateY') ||
              (i === 'perspective') ||
              (i === 'transformOrigin'))) { continue; }
  
            if (i[0] !== '_') {
              if (use3d && (i === 'scale')) {
                re.push(i + "3d(" + this[i] + ",1)");
              } else if (use3d && (i === 'translate')) {
                re.push(i + "3d(" + this[i] + ",0)");
              } else {
                re.push(i + "(" + this[i] + ")");
              }
            }
          }
        }
  
        return re.join(" ");
      }