public function delPhoto($photo_id)
    {
        if (!is_numeric($photo_id) || 0 >= $photo_id) {
            throw new InvalidArgumentException(
                "Api::delPhoto photo_id field should be positive integer");
        }

        /** @var $command \Guzzle\Service\Command\AbstractCommand */
        $command = $this->client->getCommand('DeletePhoto',array('photo_id' => $photo_id));

        return $this->executeCommand($command);
    }