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.
the
flatten
method is overridden for the tests, so this solution doesn't work at allyour solution doesn't work if initial array contains any other arrays inside - check test cases