public void A_FlattenMerge_must_work_in_the_nominal_case()
{
var task = Source.From(new[] {Src10(0), Src10(10), Src10(20), Src10(30)})
.MergeMany(4, s => s)
.RunWith(ToSet, Materializer);
task.Wait(TimeSpan.FromSeconds(1)).Should().BeTrue();
task.Result.ShouldAllBeEquivalentTo(Enumerable.Range(0, 40));
}