text: var Rx = require('rxjs/Rx');
  
  Rx.Observable.interval(1000).take(4)
      .map((valueOuter) => Rx.Observable.interval(400).take(4).map((valueInner) => {
          return "Outer:" + valueOuter + ", Inner:" + valueInner;
      }))
      .mergeAll()
      .subscribe(console.log);