docs: function doOnEvent(scope, events, cb) {
          var i, eventName;
          var fns = [];  // these will hold callbacks for removing listeners
  
          // set up the watchers if they exist
          if (events && cb) {
              for (i = 0; i < events.length; i++) {
                  eventName = events[i];
                  fns.push(eventBus.on(eventName, cb));
              }
  
              // make sure handlers are destroyed along with scope
              scope.$on('$destroy', function () {
                  for (i = 0; i < fns.length; i++) {
                      fns[i]();
                  }
              });
          }
      }