Ok, thanks for the reply!
So this means that: (notice how only the last digit changes in the inputs)

• 1234321234321235 gives 123 => 432 => 123 => 432 => 123 => 5
• 1234321234321234 gives 1234 => 321 => 234 => 321 => 234

and we could produce examples arbitrarily long with only the last digits that differs while the output is completely different.

I mean that's interesting but it's a tiny bit more challenging to implement than I first thought! :D

What is [1, 2, 3, 4, 5, 4, 3, 2, 3, 4] supposed to return?

"1:5+1,4:3-1,3,4" or "1:4+1,5:3-1,2:3+1"?

Thanks!