presto-geospatial/src/main/java/io/prestosql/plugin/geospatial/GeoFunctions.java/GeoFunctions/stX
class GeoFunctions:    @SqlNullable
    @Description("Return the X coordinate of the point")
    @ScalarFunction("ST_X")
    @SqlType(DOUBLE)
    public static Double stX(@SqlType(GEOMETRY_TYPE_NAME) Slice input)
    {
        OGCGeometry geometry = deserialize(input);
        validateType("ST_X", geometry, EnumSet.of(POINT));
        if (geometry.isEmpty()) {
            return null;
        }
        return ((OGCPoint) geometry).X();
    }