public async Task Test_await_Task_result()
{
var sut = new Concurrency();
// Also unlike Go's goroutine, Task can 'returns' result after the task completed.
var result = await sut.BenchmarkSayAsync("Hi", TimeSpan.FromMilliseconds(5));
// note: there's always overhead to run async operations.
Assert.True(result > TimeSpan.FromMilliseconds(25));
}