docs: def enumerate(self, name, start=1):
          """
          Enumerates all rows such that the pseudo key and the ordinal number are a unique key.
  
          :param str name: The key holding the ordinal number.
          :param int start: The start of the ordinal numbers. Foreach pseudo key the first row has this ordinal number.
          """
          for pseudo_key, rows in self._rows.items():
              rows = self._rows_sort(rows)
              ordinal = start
              for row in rows:
                  row[name] = ordinal
                  ordinal += 1
              self._rows[pseudo_key] = rows