presto-main/src/main/java/io/prestosql/sql/planner/SubqueryPlanner.java/SubqueryPlanner/visitProject
class SubqueryPlanner:        @Override
        public PlanNode visitProject(ProjectNode node, RewriteContext<Void> context)
        {
            ProjectNode rewrittenNode = (ProjectNode) context.defaultRewrite(node);

            Assignments assignments = rewrittenNode.getAssignments()
                    .rewrite(expression -> replaceExpression(expression, mapping));

            return new ProjectNode(node.getId(), rewrittenNode.getSource(), assignments);
        }