default is a an empty list and help is a string '(use multiple --exclude to exclude multiple apps/models).'. call the method parser.add_argument with 6 arguments: string '-n', string '--natural', action is string 'store_true', dest is string 'use_natural_keys',
parser . add_argument ( '-n' , '--natural' , action = 'store_true' , dest = 'use_natural_keys' , default = False , help = 'Use natural keys if they are available (deprecated: use --natural-foreign instead).' )