How to use the keystonemiddleware.auth_token._base.AUTHTOKEN_GROUP function in keystonemiddleware

def _get_auth_plugin(self):
        # NOTE(jamielennox): Ideally this would use load_from_conf_options
        # however that is not possible because we have to support the override
        # pattern we use in _conf_get. This function therefore does a manual
        # version of load_from_conf_options with the fallback plugin inline.

        group = self._conf_get('auth_section') or _base.AUTHTOKEN_GROUP

        # NOTE(jamielennox): auth_plugin was deprecated to auth_type. _conf_get
        # doesn't handle that deprecation in the case of conf dict options so
        # we have to manually check the value
        plugin_name = (self._conf_get('auth_type', group=group)
                       or self._conf.get('auth_plugin'))

        if not plugin_name:
            return _auth.AuthTokenPlugin(
                log=self.log,
                auth_admin_prefix=self._conf_get('auth_admin_prefix',
                                                 group=group),
                auth_host=self._conf_get('auth_host', group=group),
                auth_port=self._conf_get('auth_port', group=group),
                auth_protocol=self._conf_get('auth_protocol', group=group),
                identity_uri=self._conf_get('identity_uri', group=group),

    def _conf_get(self, name, group=_base.AUTHTOKEN_GROUP):
        # try config from paste-deploy first
        if name in self._conf:
            return self._conf[name]
        elif self._local_oslo_config:
            return self._local_oslo_config[group][name]
        else:
            return CONF[group][name]

' check as valid. Setting this true will become the default'
                ' in a future release and should be enabled if possible.'),
    cfg.StrOpt('service_type',
               help='The name or type of the service as it appears in the'
               ' service catalog. This is used to validate tokens that have'
               ' restricted access rules.'),
]


CONF = cfg.CONF
CONF.register_opts(_OPTS, group=_base.AUTHTOKEN_GROUP)
loading.register_auth_conf_options(cfg.CONF, _base.AUTHTOKEN_GROUP)


auth_token_opts = [
    (_base.AUTHTOKEN_GROUP, _OPTS + loading.get_auth_common_conf_options()),
]

__all__ = (
    'list_opts',
)


def list_opts():
    """Return a list of oslo_config options available in auth_token middleware.

    The returned list includes the non-deprecated oslo_config options which may
    be registered at runtime by the project. The purpose of this is to allow
    tools like the Oslo sample config file generator to discover the options
    exposed to users by this middleware.

    Deprecated Options should not show up here so as to not be included in