Test Delay with FlatMap operator

TestDelayAndFlatMap.kt

fun `test delay`() {
    Observable.just(listOf(1,2,3,4,5))
        .flatMap { nums ->
            val obs = mutableListOf<Observable<Int>>()
            for (i in nums) {
                obs.add(Observable.just(i).delay(i.toLong(), TimeUnit.MILLISECONDS))
            }
            Observable.merge(obs)
        }
        .subscribe { println("$it") }
    Thread.sleep(6000)
}

Expected log message should be

1
2
3
4
5