public function getAccessToken($oauthToken, $oauthVerifier)
    {
        //Oauth1 plugin to get access tokens!
        $oauth = new Oauth1(array(
            'consumer_key'    => $this->credentials->getConsumerKey(),
            'consumer_secret' => $this->credentials->getConsumerSecret(),
            'token'           => $oauthToken,
            'verifier'        => $oauthVerifier
        ));

        //attach oauth to request
        $this->guzzleClient->getEmitter()->attach($oauth);

        //POST to 'oauth/access_token' - get access tokens
        $accessTokenResponse = $this->guzzleClient->post(
            Config::get('oauth_access_token'),
            array(
                'auth' => 'oauth'
            )
        );

        //handle response
        $response = array();
        parse_str($accessTokenResponse->getBody(), $response);

        //set access tokens
        $this->credentials
            ->setAccessToken($response['oauth_token'])
            ->setAccessTokenSecret($response['oauth_token_secret']);

        return $response; //contains 'oauth_token', 'oauth_token_secret', 'user_id' and 'screen_name'
    }