.

To explicitly tell you what you do not need to support.

Kata is clear that all input will be valid. Pointing out invalid input does no harm.

It is even tougher now, as I require a O(n) join function.

You need to traverse every single element.

Kept in both cases.

Did you try this method and succeed? I don't care for cheaters. They cheat only themselves. There is so many ways to cheat at CW.
I'm afraid that your method is more time consuming to cheat than to find a solution.
Anyway more than 500 CW have passed the JS kata so nothing can be changed.
Thanks for your post.LOL.

I can't speak for the tests, but I believe it should produce the following thing:

jane = {
  head: {
    eyes: [
      {
        color: 'blue',
        pupil: {
          color: 'black'
        }
      },
      {
        color: 'blue',
        pupil: {
          color: 'black'
        }
      }
    ]
  }
}

Wow, good eye. What a debugger you must be! :)

It's because the validation code is using hash algorithm, and hash collision occurs frequently.

Fixed

Well, you approved the kata so you can edit the kata yourself to fix it.

It also means you're responsible for future kata issues ;-)

Fixed

Wait ... I just found a genuine Issue with the Python version of this Kata but I can't throw it back into Beta QAQ

That is no longer the case - fortunately, all 4 Issues raised on this Kata were merely opinions and did not reflect any major flaws within the Kata itself so I resolved them all and approved it :D