code: def main():
      
      parser = argparse.ArgumentParser(description = 'XMPP version checker',
                                      parents = [XMPPSettings.get_arg_parser()])
      parser.add_argument('source', metavar = 'SOURCE', 
                                          help = 'Source JID')
      parser.add_argument('target', metavar = 'TARGET', nargs = '?',
                              help = 'Target JID (default: domain of SOURCE)')
      parser.add_argument('--debug',
                          action = 'store_const', dest = 'log_level',
                          const = logging.DEBUG, default = logging.INFO,
                          help = 'Print debug messages')
      parser.add_argument('--quiet', const = logging.ERROR,
                          action = 'store_const', dest = 'log_level',
                          help = 'Print only error messages')
      args = parser.parse_args()
      settings = XMPPSettings()
      settings.load_arguments(args)
      
      if settings.get("password") is None:
          password = getpass("{0!r} password: ".format(args.source))
          if sys.version_info.major < 3:
              password = password.decode("utf-8")
          settings["password"] = password
  
      if sys.version_info.major < 3:
          args.source = args.source.decode("utf-8")
  
      source = JID(args.source)
  
      if args.target:
          if sys.version_info.major < 3:
              args.target = args.target.decode("utf-8")
          target = JID(args.target)
      else:
          target = JID(source.domain)
  
      logging.basicConfig(level = args.log_level)
  
      checker = VersionChecker(source, target, settings)
      try:
          checker.run()
      except KeyboardInterrupt:
          checker.disconnect()
docs: Parse the command-line arguments and run the tool.