code: def add_config(parser):
    
    # the default config path
    default_config_path = config.get_heron_conf_dir()
  
    parser.add_argument(
        '--config-path',
        metavar='(a string; path to cluster config; default: "' + default_config_path + '")',
        default=os.path.join(config.get_heron_dir(), default_config_path))
  
    return parser
docs: add config