presto-geospatial/src/main/java/io/prestosql/plugin/geospatial/GeoFunctions.java/GeoFunctions/stInteriorRingN
class GeoFunctions:    @SqlNullable
    @Description("Returns the interior ring element at the specified index (indices start at 1)")
    @ScalarFunction("ST_InteriorRingN")
    @SqlType(GEOMETRY_TYPE_NAME)
    public static Slice stInteriorRingN(@SqlType(GEOMETRY_TYPE_NAME) Slice input, @SqlType(INTEGER) long index)
    {
        OGCGeometry geometry = deserialize(input);
        validateType("ST_InteriorRingN", geometry, EnumSet.of(POLYGON));
        OGCPolygon polygon = (OGCPolygon) geometry;
        if (index < 1 || index > polygon.numInteriorRing()) {
            return null;
        }
        OGCGeometry interiorRing = polygon.interiorRingN(toIntExact(index) - 1);
        return serialize(interiorRing);
    }