@chalin : I scraped through [Idomatic Dart](https://www.dartlang.org/articles/idiomatic-dart/) and [Style Guide](https://www.dartlang.org/articles/style-guide/), but could not find the reference to  `_` , I presume then it should be something specific to `angular.dart` or `dart2js`, it would be great if you can link me to it. thanks!