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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.
These are not unnecessary, as the solve the other diagonal
[0,0,x], [0,x,0], [x,0,0]
So
join('-')
stops /222/ from solving your example as it add an extra character at the end of each row.