"Santa's Envoy"'s AsObservable Test

using System;
using System.Linq;
using System.Collections.Generic;

namespace System
{
    public static class DelegateEx
    {
        public static IObservable<IEvent<TEventArgs>> AsObservable<TEventArgs>(this EventHandler<TEventArgs> @event) where TEventArgs : EventArgs
        {
            return Observable.FromEvent<TEventArgs>(handler => @event += handler, handler => @event -= handler);
        }
    }

    public class Program
    {
        public static EventHandler<EventArgs> SomeEvent;

        static void Main()
        {
            var synthesis = new System.Speech.Synthesis.SpeechSynthesizer();

            SomeEvent.AsObservable().Subscribe(args => synthesis.Speak(args.Sender.ToString()));

            synthesis.Speak(SomeEvent == null ? "SomeEvent is null." : "SomeEvent is not null.");
        }
    }
}