presto-parser/src/main/java/io/prestosql/sql/ExpressionFormatter.java/Formatter/visitIntervalDataType
class Formatter:        @Override
        protected String visitIntervalDataType(IntervalDayTimeDataType node, Void context)
        {
            StringBuilder builder = new StringBuilder();

            builder.append("INTERVAL ");
            builder.append(node.getFrom());
            if (node.getFrom() != node.getTo()) {
                builder.append(" TO ")
                        .append(node.getTo());
            }

            return builder.toString();
        }