presto-client/src/main/java/io/prestosql/client/IntervalYearMonth.java/IntervalYearMonth/formatMonths
class IntervalYearMonth:    public static String formatMonths(int months)
    {
        if (months == Integer.MIN_VALUE) {
            return INT_MIN_VALUE;
        }

        String sign = "";
        if (months < 0) {
            sign = "-";
            months = -months;
        }

        return format("%s%d-%d", sign, months / 12, months % 12);
    }