code: def _parse_arg(valid_classifications):
      
  
      parser = argparse.ArgumentParser(
          description=('The country converter (coco): a Python package for '
                       'converting country names between '
                       'different classifications schemes. '
                       'Version: {}'.format(__version__)
                       ), prog='coco', usage=('%(prog)s --names --src --to]'))
  
      parser.add_argument('names',
                          help=('List of countries to convert '
                                '(space separated, country names consisting of '
                                'multiple words must be put in quotation marks).'
                                'Possible classifications: ' +
                                ', '.join(valid_classifications) +
                                '; NB: long, official and short are provided '
                                'as shortcuts for the names classifications'
                                ), nargs='*')
      parser.add_argument('-s', '--src', '--source', '-f', '--from',
                          help=('Classification of the names given, '
                                '(default: inferred from names)'))
      parser.add_argument('-t', '--to',
                          help=('Required classification of the passed names'
                                '(default: "ISO3"'))
      parser.add_argument('-o', '--output_sep',
                          help=('Seperator for output names '
                                '(default: space), e.g. "," '))
      parser.add_argument('-n', '--not_found',
                          default='not found',
                          help=('Fill in value for none found entries. '
                                'If "None" (string), keep the input value '
                                '(default: not found)'))
      parser.add_argument('-a', '--additional_data',
                          help=('Data file with additional country data'
                                '(Same format as the original data file - '
                                'utf-8 encoded tab separated data, same '
                                'column headers as in the general country '
                                'data file; default: not found)'))
  
      args = parser.parse_args()
      args.src = args.src or None
      args.to = args.to or 'ISO3'
      args.not_found = args.not_found if args.not_found != 'None' else None
      args.output_sep = args.output_sep or ' '
  
      return args
docs: Command line parser for coco
  
      Parameters
      ----------
  
      valid_classifications: list
          Available classifications, used for checking input parameters.
  
      Returns
      -------
  
      args : ArgumentParser namespace