I haven't used this in a long time, so maybe I have something set wrong, but when I tried my initial idea using a Set it kept throwing an error saying undefined wasn't a function. I had to resort to an object to merge the numbers. The language selection would only allow Node ~6.x or 8.x (It think were the two enabled), 10.x was disabled. I thought it was part of the requirements, but now I see lots of solutions using Set.
Not sure what gives.