code: def parse():
      
  
      # Build the list of subcommand modules
      modnames = [mod for (_, mod, _)
                  in pkgutil.iter_modules(payu.subcommands.__path__,
                                          prefix=payu.subcommands.__name__ + '.')
                  if mod.endswith('_cmd')]
  
      subcmds = [importlib.import_module(mod) for mod in modnames]
  
      # Construct the subcommand parser
      parser = argparse.ArgumentParser()
      parser.add_argument('--version', action='version',
                          version='payu {0}'.format(payu.__version__))
  
      subparsers = parser.add_subparsers()
  
      for cmd in subcmds:
          cmd_parser = subparsers.add_parser(cmd.title, **cmd.parameters)
          cmd_parser.set_defaults(run_cmd=cmd.runcmd)
  
          for arg in cmd.arguments:
              cmd_parser.add_argument(*arg['flags'], **arg['parameters'])
  
      # Display help if no arguments are provided
      if len(sys.argv) == 1:
          parser.print_help()
      else:
          args = vars(parser.parse_args())
          run_cmd = args.pop('run_cmd')
          run_cmd(**args)
docs: Parse the command line inputs and execute the subcommand.