Creates a real SinkTIn, TMat upon receiving the first element. Internal SinkTIn, TMat will not be created if there are no elements, because of completion or error. If sinkFactory throws an exception and the supervision decision is Stop the Task will be completed with failure. For all other supervision options it will try to create sink with next element. fallback will be executed when there was no elements and completed is received from upstream.

public static Sink<TIn, Task<TMat>> LazySink<TIn, TMat>(
	Func<TIn, Task<Sink<TIn, TMat>>> sinkFactory,
	Func<TMat> fallback
)

static member LazySink : 
        sinkFactory : Func<'TIn, Task<Sink<'TIn, 'TMat>>> * 
        fallback : Func<'TMat> -> Sink<'TIn, Task<'TMat>>