code: public function exec($calcId = null)
      {
          if (is_null($calcId)) {
              $calcId = $this->queryGetCalcId->exec();
          }
          if (!isset($this->cachedIds[$calcId])) {
              $ids = [];
              $where = \Praxigento\BonusHybrid\Repo\Data\Registry\SignUpDebit::A_CALC_REF . '=' . (int)$calcId;
              $rs = $this->daoRegistry->get($where);
              /** @var \Praxigento\BonusHybrid\Repo\Data\Registry\SignUpDebit $one */
              foreach ($rs as $one) {
                  $ids[] = $one->getCustomerRef();
              }
              $this->cachedIds[$calcId] = $ids;
          }
          return $this->cachedIds[$calcId];
      }
docs: Get IDs of the customers who was processed in Sign Up Volumes Debit calculation.
  
  @param int|null $calcId ID of the calculation or null for the last one
  @return array of customers ids who was processed in Sign Up Volume Debit.