code: def _delete_extraneous_files(self):
          # type: (Downloader) -> None
          
          logger.info('attempting to delete {} extraneous files'.format(
              len(self._delete_after)))
          for file in self._delete_after:
              if self._general_options.dry_run:
                  logger.info('[DRY RUN] deleting local file: {}'.format(
                      file))
              else:
                  if self._general_options.verbose:
                      logger.debug('deleting local file: {}'.format(file))
                  try:
                      file.unlink()
                  except OSError as e:
                      logger.error('error deleting local file: {}'.format(
                          str(e)))
docs: Delete extraneous files cataloged
          :param Downloader self: this