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.
All numbers are equal except for one. Try to find it!
Well, returning 2.0 isn't really an error. The description didn't define the behavior for invalid inputs. From the description, "There is an array with some numbers. All numbers are equal except for one." Your list doesn't match the expectations for this kata, so I'm not sure what you expected to be returned.
how?