presto-main/src/main/java/io/prestosql/type/IntervalYearMonthOperators.java/IntervalYearMonthOperators/subtract
class IntervalYearMonthOperators:    @ScalarOperator(SUBTRACT)
    @SqlType(StandardTypes.INTERVAL_YEAR_TO_MONTH)
    public static long subtract(@SqlType(StandardTypes.INTERVAL_YEAR_TO_MONTH) long left, @SqlType(StandardTypes.INTERVAL_YEAR_TO_MONTH) long right)
    {
        return left - right;
    }