Update the internal state with some (possibly) new columns

        :param column_names: an iterable which contains new column names

def _update_internal_column_state(self, column_names):
        """ Update the internal state with some (possibly) new columns

        :param column_names: an iterable which contains new column names
        """
        for k in column_names:
            if k not in self._column_name_idx:
                self._column_name_idx[k] = len(self._column_name_list)
                self._column_name_list.append(k)