How AwaitTweener is supposed to work in C# ?

Once you create a signal in C#

[Signal] public delegate void SomethingHappenedEventHandler();

public override void _Ready() 
{
    Tween tween = CreateTween();
    
    tween.TweenAwait(???); // only accept Signal not Signal Name
    tween.TweenProperty(this, "modulate:a", 1, duration: 2.0);
}