def AddRow(self, values):
    """Adds a row of values.

    Args:
      values (list[object]): values.

    Raises:
      ValueError: if the number of values is out of bounds.
    """
    if self._number_of_columns and len(values) != self._number_of_columns:
      raise ValueError('Number of values is out of bounds.')

    self._rows.append(values)

    if not self._number_of_columns:
      self._number_of_columns = len(values)