docs: private boolean getBestCostPlanForExpressionSubQueries(Set<AbstractExpression> subqueryExprs) {
          int nextPlanId = m_planSelector.m_planId;
  
          for (AbstractExpression expr : subqueryExprs) {
              assert(expr instanceof SelectSubqueryExpression);
              if (!(expr instanceof SelectSubqueryExpression)) {
                  continue; // DEAD CODE?
              }
  
              SelectSubqueryExpression subqueryExpr = (SelectSubqueryExpression) expr;
              StmtSubqueryScan subqueryScan = subqueryExpr.getSubqueryScan();
              nextPlanId = planForParsedSubquery(subqueryScan, nextPlanId);
              CompiledPlan bestPlan = subqueryScan.getBestCostPlan();
              if (bestPlan == null) {
                  return false;
              }
  
              subqueryExpr.setSubqueryNode(bestPlan.rootPlanGraph);
              // The subquery plan must not contain Receive/Send nodes because it will be executed
              // multiple times during the parent statement execution.
              if (bestPlan.rootPlanGraph.hasAnyNodeOfType(PlanNodeType.SEND)) {
                  // fail the whole plan
                  m_recentErrorMsg = IN_EXISTS_SCALAR_ERROR_MESSAGE;
                  return false;
              }
          }
          // need to reset plan id for the entire SQL
          m_planSelector.m_planId = nextPlanId;
  
          return true;
      }