.

I added some additional info about "what is a hostname" but other than that the above comment stands. I don't see a way to include test cases without giving away the answer. This is in line with many other "puzzle" problems, so I think it's reasonable.

I don't think there's an easy way to add tests without giving away the answers. Do you have an example description that is more descriptive?

try to expand the equation for the fist few cycles, and you will see how this equation works.

This kata was originally coded for Javascript, which somehow manages to make it easier to work with Unicode than Python 2.x, despite its reputation (which is slowly being shed) for not having much in the way of Unicode support. The purpose of requiring Unicode for this kata is to help the people completing it be able to generalize the algorithm to any set of symbols rather than whatever alphabet they're familiar with. The fact that Python 2.x doesn't make it particularly easy to work with Unicode is something I see as a major flaw in Python 2.x. A lot of places still exclusively use Python 2.x over Python 3 (which are effectively two separate languages to me at this point). Meanwhile, if I'm writing code in any language, knowing how to work with a Unicode format is pretty high up on my list of things I want to know about that language.

I am unable to change any tests, as they are locked after a certain number of solutions are submitted.

You're meant to just abbreviate strings of alphabetic characters, so any other characters should be left intact. The whole point of a kata is to write a solution that passes the tests, not to change the tests so that your solution passes. Unless there's an actual bug, then really the onus is on the coder.

If you have problems understanding the kata, or can't figure out what the bug is with your code, feel free to ask those questions.

Could you give me the regex itself, please? Without the comments and such. I tried to just remove the comments, but it seems I didn't do it right...

Looks like you're treating a string as a single word. There can be multiple words in a string, and each of them needs to be checked and re-rendered.

Could you paste your code in a code block, so I can check it out?