code: private function createOperation($trans, $dsBegin)
      {
          $datePerformed = $this->hlpDate->getUtcNowForDb();
          $req = new \Praxigento\Accounting\Api\Service\Operation\Create\Request();
          $req->setOperationTypeCode(Cfg::CODE_TYPE_OPER_PV_WRITE_OFF);
          $req->setDatePerformed($datePerformed);
          $req->setTransactions($trans);
          $period = substr($dsBegin, 0, 6);
          $note = "PV Write Off ($period)";
          $req->setOperationNote($note);
          $resp = $this->servOperation->exec($req);
          $result = $resp->getOperationId();
          return $result;
      }
docs: Register new operation.
  
  @param \Praxigento\Accounting\Repo\Data\Transaction[] $trans
  @param string $dsBegin
  @return int operation ID
  @throws \Exception