A Sink< TIn, TMat> that materializes into a Task< TResult> of the last value received. If the stream completes before signaling at least a single element, the Task will be return a default value. If the stream signals an error errors before signaling at least a single element, the Task will be failed with the streams exception.

public static Sink<TIn, Task<TIn>> LastOrDefault<TIn>()

static member LastOrDefault : unit -> Sink<'TIn, Task<'TIn>>