def METHOD_NAME(self) -> _SubParsersAction:
    """Add the subparsers holder.
    :raises ValueError: if zero or more than one subcommand is found
    :returns: The subparsers action
    """
    subcommand_value = [
        entry for entry in self._config.entries if entry.subcommand_value is True
    ]
    if len(subcommand_value) == 0:
        msg = "No entry with subparser value defined"
        raise ValueError(msg)
    if len(subcommand_value) > 1:
        msg = "Multiple entries with subparser value defined"
        raise ValueError(msg)
    entry = subcommand_value[0]
    return self.parser.add_subparsers(
        title=entry.short_description,
        dest=entry.name,
        metavar="{subcommand} --help",
    )