Rx IgnoreElements and change sequence type

IgnoreElements`2.cs

using System;

public static class ObservableExtensions
{
    public static IObservable<TResponse> IgnoreElements<TSource, TResponse>(this IObservable<TSource> sequence) => new IgnoreElementsObservable<TSource, TResponse>(sequence);

    sealed class IgnoreElementsObservable<TSource, TResult> : IObservable<TResult>
    {
        readonly IObservable<TSource> _sequence;

        public IgnoreElementsObservable(IObservable<TSource> sequence) => _sequence = sequence;

        public IDisposable Subscribe(IObserver<TResult> observer) => _sequence.Subscribe(new IgnoreElmentsObserver<TSource, TResult>(observer));
    }

    sealed class IgnoreElmentsObserver<TSource, TResult> : IObserver<TSource>
    {
        readonly IObserver<TResult> _observer;

        public IgnoreElmentsObserver(IObserver<TResult> observer) => _observer = observer;

        public void OnCompleted() => _observer.OnCompleted();

        public void OnNext(TSource value)
        {
            // ignore
        }

        public void OnError(Exception error) => _observer.OnError(error);
    }
}