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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.
because without
lastIndexOfyou'll get a sum of the total counts of each repeated charCan someone go through the filter method with me on this one? I am confused by the use of lastIndexOf. Why can't the condition just be if(arr.indexOf(val) !== i?
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