public function setUserNick($user_id, $nick)
    {

        if (!is_numeric($user_id) || 0 >= $user_id) {
            throw new InvalidArgumentException(
                "Api::setUserNick user_id field should be positive integer", 404);
        }
        if (!is_string($nick) || 0 >= strlen($nick)) {
            throw new InvalidArgumentException(
                "APi::setUserNick nick must be a non-empty string", 404);
        }

        $command = $this->client->getCommand(
            'SetUserNick',array('id' => $user_id,'nick' => $nick));

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