def draw_decision_node(_box, context, _bounding_box):
    """
    Draw diamond shape, which represents decision and merge nodes.
    """
    cr = context.cairo
    r = 15
    r2 = r * 2 / 3
    cr.move_to(r2, 0)
    cr.line_to(r2 * 2, r)
    cr.line_to(r2, r * 2)
    cr.line_to(0, r)
    cr.close_path()
    cr.stroke()
