def batch_idx(self) -> int:
        """Returns the current batch index (within this epoch)"""
        # use `ready` instead of `completed` in case this is accessed after `completed` has been increased
        # but before the next `ready` increase
        return self.batch_progress.current.ready - 1
Returns the current batch index (within this epoch)
src/lightning/pytorch/loops/training_epoch_loop.py