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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.
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Is it a solution when, instead of implementing the solution, the function just calls another function that solves the problem?
Your writing is really concise, but I find it executes two extra operations. Under the hood, it converts to boolean, the main intent, then operates "!" twice.
Plus it is harder to read, as the double negation isn't the main propose of the code, but the undelrying conversion that takes place.