public static Shape2 Normalize(this Shape2 shape)
{
var(bi, filter) = Indexer.DistinctBi(shape.Points);
return(new Shape2
{
Points = shape.Points.Index().Where(i => filter[i]).Select(i => shape.Points[i]).ToArray(),
Convexes = shape.Convexes.Transform(i => bi[i])
});
}