def __class_getitem__(cls, config_class: type[Config]):
        """Eliminates the need to write `config_class = FooConfig` when subclassing SubConfig[FooConfig]."""
        name = f'{cls.__name__}[{config_class.__name__}]'
        return type(name, (cls,), dict(config_class=config_class))
Eliminates the need to write `config_class = FooConfig` when subclassing SubConfig[FooConfig].
mkdocs/config/config_options.py