C#7: Underscore ( _ ) & Star ( * ) in Out variable

Question

I was reading about new out variable features in C#7 here. I have two questions:

1. It says

   We allow \"discards\" as out parameters as w

Answer 1

Regarding the first question

I guess this is just an info and not a new feature of C#7 because we can do so in pre C#7.0 too.

var _;
if (Int.TryParse(str, out _))
    // ...

The novelty is that you dont have to declare _ anymore inside or outside the expression and you can just type

int.TryParse(s, out _);

Try to do this one liner pre C#7:

private void btnDialogOk_Click_1(object sender, RoutedEventArgs e)
{
     DialogResult = int.TryParse(Answer, out _);
}