@ScalarFunction
    @Description("estimated cardinality of an SfmSketch object")
    @SqlType(StandardTypes.BIGINT)
    public static long cardinality(@SqlType(SfmSketchType.NAME) Slice serializedSketch)
    {
        return SfmSketch.deserialize(serializedSketch).cardinality();
    }
@Test
    public void testCardinality()
    {
        SfmSketch sketch = createSketch(1, 10_000, 4);
        assertEquals(SfmSketchFunctions.cardinality(sketch.serialize()), sketch.cardinality());
    }