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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.
That is absolutely idiotic. The task, I mean. The solution is genius though.
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Yes, but its bad practice to modify the input data.
Actually it's no requirement that the provided data should not be modified.
A harmless named function modifying its argument(s) is definitely not best practice, but a recipe for long debug sessions.