code: private function has(array &$list, $oid, StockUnitInterface $unit)
      {
          if (!isset($list[$oid])) {
              return false;
          }
  
          return false !== $this->find($list, $oid, $unit);
      }
docs: Returns whether the unit exists into the given list for the given object identifier.
  
  @param array              $list
  @param string             $oid
  @param StockUnitInterface $unit
  
  @return bool