constructor(private _mockConfig: MockConfig) {
   if (_mockConfig['elements']) {
     this._elements = _mockConfig['elements'] as FantasyObservable;
   } else {
     this._elements = adapt(xs.empty());
   }
 }

 constructor(private _mockConfig: MockConfig) {
   if (_mockConfig.elements) {
     this._elements = _mockConfig.elements as FantasyObservable<any>;
   } else {
     this._elements = adapt(xs.empty());
   }
 }

 constructor(private _streamAdapter: StreamAdapter,
             private _mockConfig: MockConfig) {
   if (_mockConfig.elements) {
     this._elements = _mockConfig.elements;
   } else {
     this._elements = _streamAdapter.adapt(xs.empty(), xsSA.streamSubscribe);
   }
 }

 .map((e: KeyboardEvent) => {
   switch (e.keyCode) {
     case 188:
       return xs.of('decrement');
     case 190:
       return xs.of('increment');
     default:
       return xs.empty();
   }
 }).flatten()

  public events(eventType: string, options?: EventsFnOptions): any {
    const streamForEventType = this._mockConfig[eventType] as any;
    const out: DevToolEnabledSource & FantasyObservable = adapt(
      streamForEventType || xs.empty(),
    );

    out._isCycleSource = 'MockedDOM';

    return out;
  }

 .map(i => {
   if (i % 2 === 1) {
     return child(sources, i);
   } else {
     return {
       HTTP: xs.empty(),
       DOM: xs.of(''),
     };
   }
 });

  it('propagates errors', done => {
    const Time = timeDriver(xs.empty());

    xs.throw(new Error())
      .compose(Time.debounce(1))
      .addListener({
        error(err: Error) {
          done();
          Time.dispose();
        },
      });
  });

 public events(eventType: string, options: EventsFnOptions): any {
   const mockConfig = this._mockConfig;
   const keys = Object.keys(mockConfig);
   const keysLen = keys.length;
   for (let i = 0; i < keysLen; i++) {
     const key = keys[i];
     if (key === eventType) {
       return mockConfig[key];
     }
   }
   return this._streamAdapter.adapt(xs.empty(), xsSA.streamSubscribe);
 }