State postal abbreviation if county or state else ``None``.

def get_statepostal(self, obj):
        """State postal abbreviation if county or state else ``None``."""
        if obj.division.level.name == DivisionLevel.STATE:
            return us.states.lookup(obj.division.code).abbr
        elif obj.division.level.name == DivisionLevel.COUNTY:
            return us.states.lookup(obj.division.parent.code).abbr
        return None