code: def on_valid_epoch_start(self, tez_trainer, **kwargs):
      if self.num_valid_steps:
          self._valid_tqdm = tqdm(
              total=self.num_valid_steps, leave=False
          )
  
file_path: tez/tez/callbacks/progress.py
imports: from tqdm.auto import tqdm
  from tez.callbacks import Callback
label_desc: Use image node_id 3 for calling the Progress obj's underlying member method code with example usage: obj.on_valid_epoch_start(tez_trainer) without return types