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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.
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Becuase it test case present not bool values. Try this code
sum([True, None])
and you will getTypeError: unsupported operand type(s) for +: 'int' and 'NoneType'
why sum() doesn't work? It seems like should count True as "1"