docs: def _step00(self, in_row, tmp_row, out_row):
          """
          Prunes whitespace for all fields in the input row.
  
          :param dict in_row: The input row.
          :param dict tmp_row: Not used.
          :param dict out_row: Not used.
          """
          for key, value in in_row.items():
              in_row[key] = WhitespaceCleaner.clean(value)
  
          return None, None