This change modernizes the utils implementation, adding type hints and

fixing up some various style and idiom issues.
The most interesting part of this is that the execute method now has

override defines to ensure that type checkers know what it's returning

based on the various arguments. Due to the way that KGB and

deprecate_non_keyword_only_args interact, some unit tests needed to be

updated to fix their expectations for called-with checks.

Ran unit tests.