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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 is good. You can make it a bit more concise if you update the regex from what you have to "/[105]/g".
This uses a character class, so for every character Regex looks at, it looks see if the character is either "1", "0", or "5".