EDIT: This relates to code in #2165 -- should likely be fixed in that PR

Looking at Metadata._get_role_and_keys() after a while... I did not do a good job of it.

Potential improvement:

• it should return only the keys for the delegated role (instead of all delegated keys and the specific Role). I was probably avoiding unnecessary allocations here but this makes the code harder to read
• does not have to return the whole role but does have to return threshold instead
• the method should be public as it's useful in applications as well
• these changes mean some changes in verify_delegate()

Something like this

    def get_keys_and_threshold(self, delegated_role: str) -> Tuple[List[Key], int]: