• Loop var |i| should be of |size_t| type.
• Will fail for |interval| of 0.

• Ruby 3.0 should be enabled (Refer this & this for more detail)

A wiki link should be replaced with detailed description and example test cases step-by-step

simple and smart . good job !

With no argument your solution will be false. As it is mentioned in kata if no argument present return all elements .

Hi,
I edited the description a bit, now the wording is:
"You will have access to a (preloaded) dictionary (called @COUNTRIES) containing id's and their corresponding length."

Is this sufficient for you?

It should be told more clearly in the description that the data is preloaded, and moreover with what name (user shouldn't have to go the the trainer to have the info).

Done.

Can you try now the forked version?

This has conflicts, can't be approved.

no interest in type so many other information, like the length
preload this is good idea
so, skip this kata

I tried again too, and it works indeed... First time, I didn't remeber that in C cast was implicit in an operation like that, maybe the parentheses I've add (somthing like (int)'f'), or a typo I didn't saw. Anyway, that's my bad, sorry!