presto-client/src/main/java/io/prestosql/client/IntervalYearMonth.java/IntervalYearMonth/toMonths
class IntervalYearMonth:    public static int toMonths(int year, int months)
    {
        try {
            return addExact(multiplyExact(year, 12), months);
        }
        catch (ArithmeticException e) {
            throw new IllegalArgumentException(e);
        }
    }