docs: def index(self, column):  # pylint: disable=C6409
          """Fetches the column number (0 indexed).
  
      Args:
        column: A string, column to fetch the index of.
  
      Returns:
        An int, the row index number.
  
      Raises:
        ValueError: The specified column was not found.
      """
          for i, key in enumerate(self._keys):
              if key == column:
                  return i
          raise ValueError('Column "%s" not found.' % column)