docs: def parse_args(args):
      ''' Parse an argument string
  
          http://stackoverflow.com/questions/18160078/
          how-do-you-write-tests-for-the-argparse-portion-of-a-python-module
      '''
      parser = argparse.ArgumentParser()
      parser.add_argument('config_file', nargs='?',
                          help='Configuration yaml file', default=None)
      parser.add_argument(
          '--log', '-l',
          help='Logging level (e.g. DEBUG, INFO, WARNING, ERROR, CRITICAL)',
          default='INFO')
      args_parsed = parser.parse_args(args)
      if not args_parsed.config_file:
          parser.error("You have to specify "
                       "a configuration file")  # pragma: no cover, sysexit
      return args_parsed