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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.
the expected result for the last test is wrong,
the fourth to last number is always different than the input one.
example:
cc = "65473632678289"
expented output = "##########4289"