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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.
This is a very tricky one - and it makes us utilize several methods that are available to the Array object. Thanks for all the hints and the tips on here! :D
Not a problem of the kata (600 guys passed the PHP version) but maybe a problem of the PHP version at CW. Report it as a CW bug if you want (Forum -> Bugs) or write yourself the case conversion.
Error: Call to undefined function mb_convert_case()
Why?
mb_convert_case — Perform case folding on a string (PHP 4 >= 4.3.0, PHP 5, PHP 7)
https://secure.php.net/manual/en/function.mb-convert-case.php