presto-main/src/main/java/io/prestosql/sql/planner/sanity/ValidateDependenciesChecker.java/Visitor/visitMarkDistinct
class Visitor:        @Override
        public Void visitMarkDistinct(MarkDistinctNode node, Set<Symbol> boundSymbols)
        {
            PlanNode source = node.getSource();
            source.accept(this, boundSymbols); // visit child

            checkDependencies(source.getOutputSymbols(), node.getDistinctSymbols(), "Invalid node. Mark distinct symbols (%s) not in source plan output (%s)", node.getDistinctSymbols(), source.getOutputSymbols());

            return null;
        }