presto-main/src/main/java/io/prestosql/type/QuantileDigestOperators.java/QuantileDigestOperators/castToBinaryReal
class QuantileDigestOperators:    @ScalarOperator(CAST)
    @SqlType(StandardTypes.VARBINARY)
    public static Slice castToBinaryReal(@SqlType("qdigest(real)") Slice slice)
    {
        return slice;
    }