def pre_validation(self, config: Config, key_name: str) -> None:
        """
        Before all options are validated, perform a pre-validation process.

        The pre-validation process method should be implemented by subclasses.
        """

        Before all options are validated, perform a pre-validation process.

        The pre-validation process method should be implemented by subclasses.
        
mkdocs/config/base.py