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

container_name = Unicode(
        'jupyter',
        help="The name of the Jupyter server container running on the user's cluster.",
        config=True)

    cluster_polling_interval = Integer(
        30,
        help="The number of seconds between polling for a user's cluster to become active.",
        config=True
    )

    # Override the default timeout to allow extra time for creating the cluster and pulling the
    # server image
    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):