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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 description specifies that you are to return the index of the firt item for which the block returns true. If you are truely expecting a boolean value returned from the block the test cases should assert that the method returns nil when the block returns a truthy value and not the actualy boolean true value.