System.Reactive.Concurrency.VirtualTimeSchedulerExtensions
public static IDisposable ScheduleAbsolute<TAbsolute, TRelative>(this VirtualTimeSchedulerBase<TAbsolute, TRelative> scheduler, TAbsolute dueTime, Action action) where TAbsolute : IComparable<TAbsolute>
public static IDisposable ScheduleRelative<TAbsolute, TRelative>(this VirtualTimeSchedulerBase<TAbsolute, TRelative> scheduler, TRelative dueTime, Action action) where TAbsolute : IComparable<TAbsolute>