How do you test async code with this?

What I meant is, I created it primarily as a small challenge for my colleagues, it was not my intention for this to be used publicly. Maybe if it waas only accessible by a link or smth.. It doesn't matter too much I guess

My bad, forgot to add test cases to example cases. Is there a way to make a kata private though?

It just creates a copy of an array, so that actual argument is not mutated. n could be ommited here, without change, making this less confusing.