Ranks can't be changed and no, the tasks ask for simple & direct mathematics concept unlike other 6kyus math-related katas

Well, reading it again, actually, doesn't it say twice the same? I think the first sentence is actually sufficient.

This is clearly stated in the first paragraph of the description.

Now I read the description, I am not exactly sure about whether it's clear enough. I think it puts pressure on the mapping only in one direction (from A to B), but I am not sure which part would clearly state that B also must map to A...

....and reverse: in the first example, R in the first word can be mapped only to T in the second word, and T in the second word can be mapped only to R in the first word.

In your example, C from the second word cannot be unambiguously mapped to any letter from the first word.

This is clearly stated in the first paragraph of the description.

Because the kata is back to draft.

Try to draw out the example - many people who tried this problem first came up with your solution. However, it might not be the optimal approach.

Please mark your post as having spoiler content next time and read this: https://docs.codewars.com/training/troubleshooting/#post-discourse

If you are given an array with multiple answers, return the lowest correct index.

Why are you returning the first array value instead when there is more than one answer?

You are totally right, that was a mistake. Just fixed it now.

Yes you did, a and cages are both references to the same list.

Thanks for review, function name is fixed.
I will edit the task description to make it clear.

I also had to change functions name.
I would consider this as 8 kyu and since so, the task is very unclear, you should probably provide better description (i.e. the task is to implement the function, which calculates manhattan_distance(x, y), where x, y are lists with the same length with more then zero elements).

Those are 2 consecutive increases, not 3.