Thread.CurrentThread.Name = "main-thread-hh";

// await Task.Run(() => Console.WriteLine("t5 = {0}", Thread.CurrentThread.Name));
Task.Run(() => Console.WriteLine("t4 = {0}", Thread.CurrentThread.Name));
// await Task.Run(() => Console.WriteLine("t5 = {0}", Thread.CurrentThread.Name));
foo();
await bar();

async Task foo() {
    Console.WriteLine("foo = {0}", Thread.CurrentThread.Name);
}

async Task bar() {
    Console.WriteLine("bar = {0}", Thread.CurrentThread.Name);
}