presto-main/src/main/java/io/prestosql/sql/planner/SubqueryPlanner.java/SubqueryPlanner/replaceExpressionsWithSymbols
class SubqueryPlanner:    private PlanNode replaceExpressionsWithSymbols(PlanNode planNode, Map<NodeRef<Expression>, Expression> mapping)
    {
        if (mapping.isEmpty()) {
            return planNode;
        }

        return SimplePlanRewriter.rewriteWith(new ExpressionReplacer(mapping), planNode, null);
    }