You don't need to. The main problem of this task is that it gives us no clue. That's why it sucks.

https://docs.codewars.com/training/troubleshooting/#print-input

Ruby

Omg, lol. thanks. I had no idea what to do.
I wish author could include brief summary at the end of what is required to do from us

Hi gileto,

Might be your comments on your code causing the issue double quotes "" , quotation marks '' and backticks `` are banned from this Kata!

Hope this helps!

I consider myself a fluent speaker but I struggled too :D

What language?

Because you have to work with the prototype in javascript, not with a function like you did, check the initial code:

String.prototype.isUpperCase = function() {
  // your code here
}