def _check_list_select_related(self, obj):

        if not isinstance(obj.list_select_related, (bool, list, tuple)):
            return must_be('a boolean, tuple or list', option='list_select_related', obj=obj, id='admin.E117')
        else:
            return []
Check that list_select_related is a boolean, a list or a tuple.
dataset/ETHPy150Open django/django/django/contrib/admin/checks.py/ModelAdminChecks._check_list_select_related