docs: def DeleteOldClientStats(self, yield_after_count,
                             retention_time
                            ):
      """Deletes ClientStats older than a given timestamp."""
  
      yielded = False
  
      while True:
        deleted_count = self._DeleteClientStats(
            limit=yield_after_count, retention_time=retention_time)
  
        # Do not yield a trailing 0 after any non-zero count has been yielded.
        # A trailing zero occurs, when an exact multiple of `yield_after_count`
        # rows were in the table.
        if not yielded or deleted_count > 0:
          yield deleted_count
          yielded = True
  
        # Return, when no more rows can be deleted, indicated by a transaction
        # that does not reach the deletion limit.
        if deleted_count < yield_after_count:
          return