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.
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Set initialValue = ['', 0] is another way to extend arr.reduce(). Good work !
a.pop() is simpler than repy on array element index. Good job !
Finally I passed. Read requirement again and again. ^_^