Async Flow

private static async Task Exec()
{
    try
    {
        await Task.Delay(1);
        await A();
    }
    catch (Exception ex)
    {
        Trace.WriteLine(ex);
    }
}
private static async Task A()
{
    await Task.Delay(1);
    await B();
}
private static async Task B()
{
    await Task.Delay(1);
    throw new ArgumentException("some error");
}