anchor.diff:        this._clock, this._persistence, Iterable<Interactor> interactors) {
       _ff = new FastForwarder(_clock);
   
  -    interactors.forEach((interactor) {
  +    for (var interactor in interactors) {
         if (_interactorsByModule.containsKey(interactor.moduleName)) {
           throw new ArgumentError.value(
               interactors,
  
positive.code: part 'src/observable.dart';
  
  class InteractionManager implements Sink<Interaction> {
    final _ctrl = new StreamController<Interaction>(sync: true);
    final _interactorsByModule = <String, Interactor>{};
    final Persistence _persistence;
    final Clock _clock;
  
negative.code:       }
  
        _interactorsByModule[interactor.moduleName] = interactor;
      };
    }
  
    Duration get currentOffset => _ff.currentOffset;
  
    @override
    void add(Interaction interaction) {
      _persistInteraction(interaction);
      _runInteraction(interaction);
    }
  
    @override
    void close() {}
  
    // TODO: We need a way to pause running timers, allow UI to pause
    void run(Function script) {
      if (_persistence.savedInteractions.isNotEmpty) {
        _ff.runFastForwardable((ff) {
  