Mypy cannot generally understand that these regex functions cannot possibly fail. Add a "must_match" helper that makes this clear for mypy. Signed-off-by: John Snow <jsnow@redhat.com> Message-Id: <20210519183951.3946870-10-jsnow@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>