Loading collection data...
Collections are a way for you to organize kata so that you can create your own training routines. Every collection you create is public and automatically sharable with other warriors. After you have added a few kata to a collection you and others can train on the kata contained within the collection.
Get started now by creating a new collection.
Your comment is a spoiler, the hint you mentioned spoils the fun!
There is no space problem. The test is (see the last one in Sample tests):
"String s = "733049910872815764";
testing(RevRot.revRot(s, 5), "330479108928157");".
Your code not working is not an issue (= a bug in the kata). Please read this: https://docs.codewars.com/training/troubleshooting/