def progress_bar_callback(self) -> Optional[ProgressBar]:
        """An instance of :class:`~lightning.pytorch.callbacks.progress.progress_bar.ProgressBar` found in the
        Trainer.callbacks list, or ``None`` if one doesn't exist."""
        for c in self.callbacks:
            if isinstance(c, ProgressBar):
                return c
        return None
An instance of :class:`~lightning.pytorch.callbacks.progress.progress_bar.ProgressBar` found in the
        Trainer.callbacks list, or ``None`` if one doesn't exist.
src/lightning/pytorch/trainer/trainer.py