ITaskObservable<T> public interface ITaskObservable<T> : IObservable<T> Documentation Code using System.Runtime.CompilerServices; namespace System.Reactive { [NullableContext(1)] [AsyncMethodBuilder(typeof(TaskObservableMethodBuilder<>))] public interface ITaskObservable<[Nullable(2)] out T> : IObservable<T> { ITaskObservableAwaiter<T> GetAwaiter(); } }