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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.
This solution is similar to mine but I think you formatted it way more cleanly that I did. I'll change my style because this is way more readible. But I do have a question, why use map instead of str.toLowerCase(). directly?