ExploreCoroutines_delay.kt

public suspend fun delay(timeMillis: Long) {
    if (timeMillis <= 0) return // don't delay
    return suspendCancellableCoroutine sc@ { cont: CancellableContinuation<Unit> ->
        // if timeMillis == Long.MAX_VALUE then just wait forever like awaitCancellation, don't schedule.
        if (timeMillis < Long.MAX_VALUE) {
            cont.context.delay.scheduleResumeAfterDelay(timeMillis, cont)
        }
    }
}

override fun scheduleResumeAfterDelay(timeMillis: Long, continuation: CancellableContinuation<Unit>) {
    postDelayed(Runnable {
        with(continuation) { resumeUndispatched(Unit) }
    }, timeMillis)
}