code: def after_val_iter(self, runner):
      if self._is_rank_zero(runner):
          runner._progress_bar.n = runner.batch_idx
          postfix = {}
          postfix.update(loss=runner.loss.item())
          runner._progress_bar.set_postfix(postfix)
  
file_path: BigDL/python/orca/src/bigdl/orca/learn/pytorch/callbacks/tqdm.py
imports: from bigdl.orca.learn.pytorch.callbacks import Callback
  from bigdl.dllib.utils.log4Error import invalidInputError
label_desc: Use image node_id 4 for calling the TqdmCallback obj's underlying member method code with example usage: obj.after_val_iter(runner) without return types