<PackageReference Include="System.Reactive" Version="6.0.0-preview.1" />

BooleanDisposable

public sealed class BooleanDisposable : ICancelable, IDisposable
Represents a disposable resource that can be checked for disposal status.
using System.Runtime.CompilerServices; namespace System.Reactive.Disposables { public sealed class BooleanDisposable : ICancelable, IDisposable { [System.Runtime.CompilerServices.Nullable(1)] internal static readonly BooleanDisposable True = new BooleanDisposable(true); private volatile bool _isDisposed; public bool IsDisposed => _isDisposed; public BooleanDisposable() { } private BooleanDisposable(bool isDisposed) { _isDisposed = isDisposed; } public void Dispose() { _isDisposed = true; } } }