reactive/AsyncRx.NET/System.Reactive.Async/System/Reactive/Concurrency/IClock.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the Apache 2.0 License.
// See the LICENSE file in the project root for more information. 

namespace System.Reactive.Concurrency
{
    public interface IClock
    {
        DateTimeOffset Now { get; }
    }
}