public function preSend(Event $e)
    {
        $validator = new NotEmpty();

        if (!isset($this->options['tokenOrLogin'])
            || !$validator->isValid($this->options['tokenOrLogin'])
        ) {
            throw new Exception\InvalidArgumentException('You need to set OAuth token!');
        }

        /* @var Http\Request $request */
        $request = $e->getTarget();

        $headers = $request->getHeaders();
        $params = array(
            'Authorization' => 'token ' . $this->options['tokenOrLogin'],
        );
        $headers->addHeaders($params);
    }