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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.
i think it's because if the for each didn't find a x.language, start it with a 0, otherwise it start with "nan" and you cant sum the nexts same languages
Try removing it.
why zero in solution ??