presto-main/src/main/java/io/prestosql/sql/planner/QueryPlanner.java/QueryPlanner/handleSubqueries
class QueryPlanner:    private PlanBuilder handleSubqueries(PlanBuilder subPlan, Node node, Iterable<Expression> inputs)
    {
        for (Expression input : inputs) {
            subPlan = subqueryPlanner.handleSubqueries(subPlan, subPlan.rewrite(input), node);
        }
        return subPlan;
    }