Sets header of table to the given tuple.

    Args:
      new_values: Tuple of new header values.

def _SetHeader(self, new_values):
        """Sets header of table to the given tuple.

    Args:
      new_values: Tuple of new header values.
    """
        row = self.row_class()
        row.row = 0
        for v in new_values:
            row[v] = v
        self._table[0] = row