code: public function getByKeyCalcCust($calcId, $custId)
      {
          $byCalc = Entity::A_CALC_REF . '=' . (int)$calcId;
          $byCust = Entity::A_CUST_REF . '=' . (int)$custId;
          $where = "($byCalc) AND ($byCust)";
          $rs = $this->get($where);
          $result = (is_array($rs)) ? reset($rs) : null;
          return $result;
      }
docs: Get entry by unique key (calcId & custId).
  
  @param int $calcId
  @param int $custId
  @return \Praxigento\BonusHybrid\Repo\Data\Downline|null