How to draw a draw2d polyline

Question

Ho do I draw a polyline with draw2d (javascript not eclipse)?

(unfortunately there is no example on draw2d.org)

So far I tried:

var polyline = new draw2d.shape.basic.PolyLine();
polyline.addPoint(30, 0);
polyline.addPoint(30, 0);
polyline.addPoint(30, 70);
polyline.addPoint(50, 50);
polyline.addPoint(70, 70);
polyline.addPoint(70, 0);
canvas.addFigure(polyline);