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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.
https://www.codewars.com/kata/5279f6fe5ab7f447890006a7/discuss#64f5b8c72b610bbbb906767f
当你一打开kata, 你会看到几行编码，这些编码是错的，你必须增加,减少或是改掉其中的代码。其背后真正原理在这里 （中文版的链接^^)