def METHOD_NAME(self, rotation):
    """
    Set the Pie/Doughnut chart rotation: the angle of the first slice.
    Args:
        rotation: First segment angle: 0 <= rotation <= 360.
    Returns:
        Nothing.
    """
    if rotation is None:
        return
    # Ensure the rotation is in Excel's range.
    if rotation < 0 or rotation > 360:
        warn(
            "Chart rotation %d outside Excel range: 0 <= rotation <= 360" % rotation
        )
        return
    self.rotation = int(rotation)