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.
u r returning something with solution
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I also have this problem, what have you found any reason
If you attempted to delete elements of an array without using the .splice() method, a blank - 'undefined' - element is left in the array at that spot. Try pushing only the elements of interest to a new array, or using splice instead of delete.