protected function initializeProductMediaGalleryValue(array $attr)
    {

        // load the value/store/parent ID
        $valueId = $attr[MemberNames::VALUE_ID];
        $storeId = $attr[MemberNames::STORE_ID];
        $entityId = $attr[MemberNames::ENTITY_ID];

        // query whether the product media gallery value already exists or not
        if ($entity = $this->loadProductMediaGalleryValue($valueId, $storeId, $entityId)) {
            return $this->mergeEntity($entity, $attr);
        }

        // simply return the attributes
        return $attr;
    }