presto-main/src/main/java/io/prestosql/sql/planner/optimizations/DistinctOutputQueryUtil.java/DistinctOutputQueryUtil/IsDistinctPlanVisitor
class DistinctOutputQueryUtil:        private IsDistinctPlanVisitor(Function<PlanNode, PlanNode> lookupFunction)
        {
            this.lookupFunction = lookupFunction;
        }