let otherThreadObservable = Observable<Int>.create{
  print("thread observable -> \(Thread.current)")
  $0.on(.next(1))
  $0.on(.next(2))
return Disposables.create()
    }.subscribeOn(ConcurrentDispatchQueueScheduler(qos: .background))

_ = otherThreadObservable.observeOn(SerialDispatchQueueScheduler(qos: .default)).subscribe{
    print("thread observable -> \(Thread.current)")
    print($0)
}
_  = readLine() // for application delay