Repair link to cgafaq.info, using web archive
def signed_area(ring):
"""Return the signed area enclosed by a ring in linear time using the
- algorithm at: http://www.cgafaq.info/wiki/Polygon_Area.
+ algorithm at: https://web.archive.org/web/20080209143651/http://cgafaq.info:80/wiki/Polygon_Area
"""
xs, ys = ring.coords.xy
xs.append(xs[1])
