def get_default_config_name(self) -> Optional[str]:
        default_config_name = None
        for config_name, metadata_config in self.items():
            if len(self) == 1 or config_name == "default" or metadata_config.get("default"):
                if default_config_name is None:
                    default_config_name = config_name
                else:
                    raise ValueError(
                        f"Dataset has several default configs: '{default_config_name}' and '{config_name}'."
                    )
        return default_config_name