protected function getUrl()
    {
        $domain = $this->urls['domain'];

        $apiVersion = $this->urls['api'];

        $jsonExt = '.json';

        if (isset($this->withMedia) && $this->withMedia === true) {
            $domain = $this->urls['upload'];
        }

        if ($this->call === 'oauth/request_token' || $this->call === 'oauth/access_token') {
            $apiVersion = '';
            $jsonExt = '';
        }

        return $domain . $apiVersion . $this->call . $jsonExt;
    }