TaskObservationOptions
Controls how completion or failure is handled when a  Task or
             Task<T> is wrapped as an  IObservable<T> and observed by
            an  IObserver<T>.
            
                
Gets a flag controlling handling of exceptions that occur after cancellation
            has been initiated by unsubscribing from the observable representing the task's
            progress.
            
Gets the optional scheduler to use when delivering notifications of the tasks's
            progress.