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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.
Sorry, I'm having this problem with Java. When the input is empty, I return "". But the test fails. What is the expected result for an empty input array?