load("docdraw.mac");
docdraw2d("figures/draw_head_type",
	xrange = [0,12],
	yrange = [0,10],
	head_length = 1,
	vector([0,1],[5,5]), /* default type */
	head_type = 'empty,
	vector([3,1],[5,5]),
	head_type = 'nofilled,
	vector([6,1],[5,5])
)$