/** with bower **/
  bower install angular-subscribe --save
  <script src="path/to/angular-subscribe/dist/angular-subscribe.js"></script>

  /** with jspm **/
  jspm install angular-subscribe --save
  import 'angular-subscribe';

  angular.module('your_module_name', [ 'angular-subscribe' ]);

  $scope.$subscribe('event', callbackFn);
  /** becomes **/
  var unsub = $rootScope.$on('event', callbackFn);
  $scope.$on('$destroy', unsub);