Slick ;)

You can see the "unpacked" equivalence of this oneliner there (sort of...: the approach is the same, but the details are different)

;)

Alllllllrighty then.

For the true test, we need to be able to pass it [NaN, NaN, NaN, NaN, Batman]

I also don't really get lambda functions, but apparently they're useful for functions you'll only use once and not need to repeat, if I understand correctly

The true mark of someone not understanding what's going on. Playing around with it, I finally got it to submit. Me thinks I have more reading up to do -_-