text: import { Observable } from 'rxjs/Observable'
  import { Scheduler } from 'rxjs/Scheduler'
  import 'rxjs/add/observable/of'
  import 'rxjs/add/observable/defer'
  import 'rxjs/add/observable/timer'
  import 'rxjs/add/observable/interval'
  import 'rxjs/add/observable/fromEvent'
  import 'rxjs/add/operator/switchMap'
  import 'rxjs/add/operator/repeat'
  import 'rxjs/add/operator/share'
  import 'rxjs/add/operator/mapTo'
  
  export { Observable, Scheduler }
  