// PROJECT-EXAMPLE
var source = new Source();
source.Changed += () => System.Console.WriteLine("Changed");
source.Raise();
class Source { public event System.Action? Changed; public void Raise() => Changed?.Invoke(); }

sealed class Progress
{
    public event Action<int>? Changed;
    public void Report(int value) => Changed?.Invoke(value);
}

var progress = new Progress();
Action<int> handler = value => UO.Print($"Progress={value}");
progress.Changed += handler;
progress.Report(1);
progress.Changed -= handler;

sealed class Signal
{
    public event EventHandler? Ready;
    public void Raise() => Ready?.Invoke(this, EventArgs.Empty);
}

var signal = new Signal();
signal.Ready += (_, _) => UO.Print("Ready");
signal.Raise();