async / await for Parallel Results

import kotlinx.coroutines.*

suspend fun fetchUserAge(id: Int): Int {
    delay(200)
    return id * 10
}

suspend fun fetchUserName(id: Int): String {
    delay(150)
    return "User $id"
}

fun main() = runBlocking {
    val start = System.currentTimeMillis()

    // Parallel — both calls overlap; total wall time ≈ max(200, 150) = 200ms
    val nameDeferred = async { fetchUserName(42) }
    val ageDeferred  = async { fetchUserAge(42) }
    val name = nameDeferred.await()
    val age  = ageDeferred.await()

    println("$name is $age years old (${System.currentTimeMillis() - start}ms)")

    // Shortcut for "run these N suspends in parallel, collect results"
    val parallel = listOf(1, 2, 3).map { async { fetchUserName(it) } }.awaitAll()
    println(parallel)
}