code: def computeVoronoiDiagram(points):
      
      siteList = SiteList(points)
      context  = Context()
      voronoi(siteList,context)
      return (context.vertices, context.edges, context.polygons)
docs: Takes a list of point objects (which must have x and y fields).
          Returns a 3-tuple of:
  
             (1) a list of 2-tuples, which are the x,y coordinates of the 
                 Voronoi diagram vertices
             (2) a list of 3-tuples (a,b,c) which are the equations of the
                 lines in the Voronoi diagram: a*x + b*y = c
             (3) a list of 3-tuples, (l, v1, v2) representing edges of the 
                 Voronoi diagram.  l is the index of the line, v1 and v2 are
                 the indices of the vetices at the end of the edge.  If 
                 v1 or v2 is -1, the line extends to infinity.