How to use the dockerspawner.DockerSpawner.extra_host_config.help function in dockerspawner

start_timeout = Integer(
        300,
        help=DockerSpawner.start_timeout.help,
        config=True)

    # Override the docker run parameters
    extra_host_config = Dict(
        {
            'volumes_from': ['swarm-data'],  # --volumes-from swarm-data
            'port_bindings': {8888: None},  # -p 8888:8888
            'restart_policy': {  # --restart always
                'MaximumRetryCount': 0,
                'Name': 'always'
            },
        },
        help=DockerSpawner.extra_host_config.help,
        config=True)

    def __init__(self, **kwargs):
        # Use a different docker client for each server
        self._client = None
        self._carina_client = None
        self._docker_config = None

        super().__init__(**kwargs)

    @property
    def client(self):
        """
        The Docker client used to connect to the user's Carina cluster
        """
        # TODO: Figure out how to configure this without overriding, or tweak a bit and call super