i didn't expect an extended test input "fo99obar100". The given test cases look like:
do_test("foobar000", "foobar001");
do_test("foo", "foo1");
do_test("foobar001", "foobar002");
do_test("foobar99", "foobar100");
do_test("foobar099", "foobar100");
do_test("", "1");
do_test("1", "2");

no way one can infere such a test case after seeing these Examples.

Haha) It's good

How did this solution pass the test with single space?

OMG, I love your solution! You're very patient

Hi @jora_ipoteka - there are many users on Codewars who are intereted in improving descriptions of katas; since you are the first person who has commented about the description of this kata, could you maybe explain specifically what you think is missing from it?

Or what condition did you not understand clearly from the given description? If this is a good observation, then a moderator can update the kata to include it, if applicable.

Very bad kata. The description DOESN'T contain all conditions of the task. I had to redo my solution many times. Don't waste your time, better go to bed.