src/transformers/trainer_callback.py/ProgressCallback/on_prediction_step
class ProgressCallback:    def on_prediction_step(self, args, state, control, eval_dataloader=None, **kwargs):
        if state.is_local_process_zero and has_length(eval_dataloader):
            if self.prediction_bar is None:
                self.prediction_bar = tqdm(total=len(eval_dataloader), leave=self.training_bar is None)
            self.prediction_bar.update(1)