def cubic_bezier(document, coords):
	"cubic bezier polyline"
	element = document.createElement('path')
	points  = [(coords[i], coords[i+1]) for i  in range(0, len(coords), 2)]
	path    = ["M%s %s" %points[0]]
	for n in xrange(1, len(points), 3):
		A, B, C = points[n:n+3]
		path.append("C%s,%s %s,%s %s,%s" % (A[0], A[1], B[0], B[1], C[0], C[1]))
	element.setAttribute('d', ' '.join(path))
	return element
cubic bezier polyline