ISubject<TSource, TResult>
Represents an object that is both an observable sequence as well as an observer.
using System.Runtime.CompilerServices;
namespace System.Reactive.Subjects
{
[System.Runtime.CompilerServices.NullableContext(2)]
public interface ISubject<in TSource, out TResult> : IObserver<TSource>, IObservable<TResult>
{
}
}