presto-main/src/main/java/io/prestosql/type/setdigest/SetDigestFunctions.java/SetDigestFunctions/cardinality
class SetDigestFunctions:    @ScalarFunction
    @SqlType(StandardTypes.BIGINT)
    public static long cardinality(@SqlType(SetDigestType.NAME) Slice digest)
    {
        return SetDigest.newInstance(digest).cardinality();
    }