Check line breaks. As I said, you use parenthesis.

> BTW, why this change to using lists instead of tuples anyway? Capabilities should be immutable after type construction and tuples are a nice way to achieve that. Is there a problem with pylint when they are tuples?

Ehm, because you are concatenating here anyway and then you call `set()` on the result. Which creates a mutable set. So because this list is just temporary is better to have a list than a tuple. And if you want immutable type, then you should not be using a set.