Set number of screen lines.

    Args:
      lines: An int, number of lines. If None, use terminal dimensions.

    Raises:
      ValueError, TypeError: Not a valid integer representation.

def SetLines(self, lines):
    """Set number of screen lines.

    Args:
      lines: An int, number of lines. If None, use terminal dimensions.

    Raises:
      ValueError, TypeError: Not a valid integer representation.
    """

    (self._cli_lines, self._cli_cols) = TerminalSize()

    if lines:
      self._cli_lines = int(lines)