Observable parallel query

ParallelQueryExtensions.cs

public static class ParallelQueryExtensions
    {
        public static IObservable<T> ToUnorderedObservable<T>(this ParallelQuery<T> query)
        {
            return Observable.Create<T>(
                obs =>
                {
                    try
                    {
                        query.WithMergeOptions(ParallelMergeOptions.NotBuffered).ForAll(obs.OnNext);
                        obs.OnCompleted();
                    }
                    catch (AggregateException e)
                    {
                        obs.OnError(e.Flatten().InnerException);
                    }
                    return Disposable.Empty;
                });
        }
    }