code: def parse_command_line() -> Namespace:
      
      import tornado.options
      parser.parse_known_args(namespace=config)
      set_loglevel()  # set new log level based on commanline option
      for k, v in vars(config).items():
          if k.startswith('log'):
              tornado.options.options.__setattr__(k, v)
      return config
docs: Parse command line options and set them to ``config``.
  
      This function skips unknown command line options. After parsing options,
      set log level and set options in ``tornado.options``.