<PackageReference Include="System.Reactive" Version="5.0.0-preview.220" />

IQbservable<T>

public interface IQbservable<T> : IQbservable, IObservable<T>
Provides functionality to evaluate queries against a specific data source wherein the type of the data is known.
using System.Runtime.CompilerServices; namespace System.Reactive.Linq { public interface IQbservable<[System.Runtime.CompilerServices.Nullable(2)] out T> : IQbservable, IObservable<T> { } }