<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def tqdm(self):
 """Add a progression bar for the current extraction."""

    with utils.async_tqdm(
        total=0, desc='Extraction completed...', unit=' file') as pbar_path:
      self._pbar_path = pbar_path
      yield