using System.Reactive.Disposables; using System.Runtime.CompilerServices; namespace System.Reactive.Linq.ObservableImpl { [System.Runtime.CompilerServices.NullableContext(1)] [System.Runtime.CompilerServices.Nullable(0)] internal sealed class Never<[System.Runtime.CompilerServices.Nullable(2)] TResult> : IObservable<TResult> { internal static readonly IObservable<TResult> Default = new Never<TResult>(); private Never() { } public IDisposable Subscribe(IObserver<TResult> observer) { if (observer == null) throw new ArgumentNullException("observer"); return Disposable.Empty; } } }