nl: and help is a string "Only dump objects with given primary keys. Accepts a comma separated list of keys. " "This option will only work when you specify one model.". call the method parser.add_argument with 5 arguments: string '-o', string '--output', default is None, dest set to string 'output',
code: parser . add_argument ( '-o' , '--output' , default = None , dest = 'output' , help = 'Specifies file to which the output is written.' )