code: def list_models(args: argparse.Namespace):
      
      try:
          git_index = GitIndex(remote=args.index_repo, username=args.username,
                               password=args.password, cache=args.cache, log_level=args.log_level)
      except ValueError:
          return 1
      for model_type, models in git_index.models.items():
          print(model_type)
          default = git_index.meta[model_type]["default"]
          for uuid, model in sorted(models.items(),
                                    key=lambda m: parse_datetime(m[1]["created_at"]),
                                    reverse=True):
              print("  %s %s" % ("*" if default == uuid else " ", uuid),
                    model["created_at"])
docs: Output the list of known models in the registry.
  
      :param args: :class:`argparse.Namespace` with "username", "password", "remote_repo" and \
                          "log_level"
      :return: None