'Returns True if the group requirement (AUTH_LDAP_REQUIRE_GROUP) is
met. Always returns True if AUTH_LDAP_REQUIRE_GROUP is None.'

def _check_required_group(self):

    required_group_dn = self.settings.REQUIRE_GROUP
    if (required_group_dn is not None):
        is_member = self._get_groups().is_member_of(required_group_dn)
        if (not is_member):
            raise self.AuthenticationFailed('User    is    not    a    member    of    AUTH_LDAP_REQUIRE_GROUP')
    return True
