code: function transition(value) {
    var RE_PROP = /^\s*([a-zA-z\-]+)/;
    var parts = value.split(/\s*,\s*/);
  
    return parts.map(function (part) {
      // extract the property if the value is for the `transition` shorthand
      if (RE_PROP.test(part)) {
        var prop = part.match(RE_PROP)[1];
        var newProp = flipProperty(prop);
        part = part.replace(RE_PROP, newProp);
      }
  
      return part;
    }).join(', ');
  }
docs: Flip properties in transitions.
  
  @param {String} value Value
  @return {String}