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.
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It means you didn't return anything, when you should've returned 42.
I only took a quick look, but treating an array as string looks like a bad idea IMO. Stick to something closer to arrays/lists.