practical_coroutines_12.kt

val customDispatcher = 
    Executors.newSingleThreadExecutor().asCoroutineDispatcher()

launch(customDispatcher) {
    println("Thread name: ${Thread.currentThread().name}")
    withContext(Dispatchers.IO) {
        delay(100)
        println("Thread name: ${Thread.currentThread().name}")
    }
    println("Thread name: ${Thread.currentThread().name}")
    println("Here to remind you that withContext 
             suspends the calling coroutine i.e. stops 
             execution of calling f()")
}

Output:
Thread name: pool-1-thread-1
Thread name: DefaultDispatcher-worker-1
Thread name: pool-1-thread-1
Here to remind you that withContext suspends the calling 
coroutine i.e. stops execution of calling f()