protected function initializeProductMediaGalleryValueToEntity(array $attr)
    {

        // load the value/entity ID
        $valueId = $attr[MemberNames::VALUE_ID];
        $entityId = $attr[MemberNames::ENTITY_ID];

        // query whether the product media gallery value to entity entity already exists or not
        if ($this->loadProductMediaGalleryValueToEntity($valueId, $entityId)) {
            return;
        }

        // simply return the attributes
        return $attr;
    }