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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.
[https://www.youtube.com/watch?v=kFLSUxMzsXY](Here you go!)
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Why not? This is the first thing which came to my mind when reading the question.
If you're talking about python, python2's xrange was renamed to range in python3. (and you shouldn't be using python2 pretty much anywhere)