I submitted the solution above and one slightly refactored variation 9 years ago. I definitely did not copy from StackOverflow and I claim my solution original. I have no idea how a number of people came up with the exact solution of mine. Note that you can see other solutions once you solved a kata. Interestingly many of the accounts above where suspended.

solutions were copy pasted from the internet (stackoverflow) probably.

'All triangles will be right isoceles.' from the Kata description.

Nice extension to a general scenario though.

really "Best Practices"

yes finally someone who knows about f strings

I loved the way it can be used in a list of synonimum/translated function for academic purposes.

For instance:

love to see it

I think struggling with this for a bit is a good way to learn the difference between instances of a class and class variables. On the other hand, I'm struggling to keep up with all the issues.

I think I'll keep it as is. If they have a hard time they can get your hint from discourse.

kruto

Haha why reinvent the wheel.

well golfed

Is there a formal proof why this is the case?

If you still have trouble understanding this, try to break this expression down into the smallest pieces and do each one separately, then you will see what they all do together.
A little hint: each character is an operator that is perfectly documented.
It can be a much bigger problem to understand why this expression solves the problem in this task.

This kata should be renamed 'time machine stock billionaire' for more flare.