def periodic_checkpoint(self, global_steps, score=None, **info):
        """
        Will only save at the end of each period

        Args:
            global_steps: the number of iterations
            score: the evaluation score for saving the best parameters.
                Currently Not supported!!!
                None when session_config.checkpoint.keep_best=False
            **info: other metadata to save in checkpoint

        Returns:
            saved(bool): whether save() is actually called or not
        """
        return self._periodic_checkpoint.save(
            score=score,
            global_steps=global_steps,
            reload_metadata=False,
            **info,
        )

        Will only save at the end of each period

        Args:
            global_steps: the number of iterations
            score: the evaluation score for saving the best parameters.
                Currently Not supported!!!
                None when session_config.checkpoint.keep_best=False
            **info: other metadata to save in checkpoint

        Returns:
            saved(bool): whether save() is actually called or not
        
surreal/learner/base.py