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.
What about sparse array, where can be empty slots?
You need to rewrite the existing "map" method, like this: Array.prototype.map = ...
Fill it with 'undefined' according to new Array() length, it seems to be working in this case
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