presto-main/src/main/java/io/prestosql/sql/relational/SqlToRowExpressionTranslator.java/Visitor/visitIntervalLiteral
class Visitor:        @Override
        protected RowExpression visitIntervalLiteral(IntervalLiteral node, Void context)
        {
            long value;
            if (node.isYearToMonth()) {
                value = node.getSign().multiplier() * parseYearMonthInterval(node.getValue(), node.getStartField(), node.getEndField());
            }
            else {
                value = node.getSign().multiplier() * parseDayTimeInterval(node.getValue(), node.getStartField(), node.getEndField());
            }
            return constant(value, getType(node));
        }