presto-main/src/main/java/io/prestosql/sql/planner/optimizations/UnaliasSymbolReferences.java/Rewriter/visitAssignUniqueId
class Rewriter:        @Override
        public PlanNode visitAssignUniqueId(AssignUniqueId node, RewriteContext<Void> context)
        {
            PlanNode source = context.rewrite(node.getSource());

            return new AssignUniqueId(node.getId(), source, node.getIdColumn());
        }