presto-main/src/main/java/io/prestosql/sql/planner/planprinter/PlanPrinter.java/PlanPrinter/visitExcept
class PlanPrinter:        @Override
        public Void visitExcept(ExceptNode node, Void context)
        {
            addNode(node, "Except");

            return processChildren(node, context);
        }