public FaceCollection(MultiPolygon3 parent)
 {
     _parent = parent;
 }
 public VertexCollection(MultiPolygon3 parent)
 {
     _parent = parent;
 }
 public EdgeColllection(MultiPolygon3 parent)
 {
     _parent = parent;
 }
 public UndirectedEdgeComparerImpl(MultiPolygon3 parent)
 {
     _parent = parent;
 }