checks: Add type annotation to extra_validator
I'll put this diff on hold while waiting for an answer on https://github.com/sissaschool/xmlschema/issues/291
Migrated from D7397 (view on Phabricator)
staging instance, all data can be removed at all time
I'll put this diff on hold while waiting for an answer on https://github.com/sissaschool/xmlschema/issues/291
Migrated from D7397 (view on Phabricator)