_PolygonObject :: (VectorStructureClass fv fc a) =>
  Prism' (GeometryStructure Polygon a fv fc) (GeometryObject a)
_PolygonObject = _Polygon .
  iso GeometryPolygon (\(GeometryPolygon a) -> a)
_PolygonObject :: (VectorStructureClass fv fc a) =>
  Prism' (GeometryStructure Polygon a fv fc) (GeometryObject a)
_PolygonObject = _Polygon .
  iso GeometryPolygon (\(GeometryPolygon a) -> a)
_PolygonObject = _Polygon .
  iso GeometryPolygon (\(GeometryPolygon a) -> a)