public IEnumerable <PolygonChanged> OutGoingForPoint(int index)
{
var changedPointPolygons = MutatePoint(index);
var insertedPointPolygons = InsertPoint(index);
var removedPointPolygons = ListUtil.Singleton(RemovePoint(index));
var changeInsertPolygons = ListUtil.New <IEnumerable <IList <PolygonChanged> > >(
changedPointPolygons.DivideInfinite(CHANGES_PER_INSERT), insertedPointPolygons.Select(
x => ListUtil.New(x))).Intertwine().SelectMany(x => x);
var combined = removedPointPolygons.Concat(changeInsertPolygons);
return(combined.Where(x => !x.NewPolygon.IsSelfIntersecting()));
}