Loading collection data...
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.
You are enumerating twice. Also you're comparing all the list again, you should compare only with what wasn't compared yet.
It's trivial in this case, but nevertheless a good habit to add a doc string, saying what a function is doing. Forgot it myself...