Leon Michalak [off-list ref] writes:
This is what I have been using currently although the perfectionist in
me says that a user could pass `--unified=-1` and the code would treat
that as if nothing was passed by the user.
The command line parser and corresponding config parser callback can
be careful to check the value they get from the end user to avoid
that, can't they?
In any case, it is PEBKAC when the end-users do that, and they
cannot complain about their --unified=-1 are ignored. We do not
have to care, and can just tell them "Don't do that, then."