code: def callbackShortHelp(option, opt, value, parser):
      '''output short help (only command line options).'''
      # clear usage and description
      parser.set_description(None)
      # parser.set_usage(None)
      # output help
      parser.print_help()
      # exit
      parser.exit(f callbackShortHelp(option, opt, value, parser):
      '''output short help (only command line options).'''
      # clear usage and description
      parser.set_description(None)
      # parser.set_usage(None)
      # output help
      parser.print_help()
      # exit
      parser.exit()
docs: output short help (only command line options).