presto-main/src/main/java/io/prestosql/type/DecimalOperators.java/DecimalOperators/calculateShortRescaleParameters
class DecimalOperators:    private static List<Object> calculateShortRescaleParameters(SpecializeContext context)
    {
        long aRescale = longTenToNth(rescaleFactor(context.getLiteral("a_scale"), context.getLiteral("b_scale")));
        long bRescale = longTenToNth(rescaleFactor(context.getLiteral("b_scale"), context.getLiteral("a_scale")));
        return ImmutableList.of(aRescale, bRescale);
    }