private val scope = CoroutineScope(SupervisorJob() + Dispatchers.Default)

fun main() = runBlocking {
    val channel = BroadcastChannel<String>(1)
    for (i in 0..20) {
        println("iteration ${i + 1} start")
        val job = scope.launch {
            channel.openSubscription()
                .receiveAsFlow()
                .collect { println("receive $it") }
        }

        scope.launch(Dispatchers.IO) {
            channel.send("$i")
        }
        delay(200)
        job.cancel()
    }
    return@runBlocking
}