How to pass data into a Listener when using Guzzle?

Question

I am using Guzzle 3.8.1 with CakePHP 2.5.6 and I am making a call to the Box API. I would like to be able to refresh my access token when it expires. The issue I am encountering is that I may be using any one of N possible access tokens and I want to be able to use the $account_id that is in scope for the function I am defining this in. I don't see how I can pass it into the Listener defined function, since I am not calling that myself. I do see that the expired access_token exists in the $event variable, but I would have to locate it and then parse it from the header that I am passing to Box. I think I could add a custom header containing the account_id, but that seems like a bad way to approach the problem. Can I somehow specify a variable in the request that wouldn't be added as part of the call to Box? Any suggestions are much appreciated, thanks!

`

public function get_folder_list ($account_id = null, $parent_folder_id = null) {
    // Get account
    $this->Account = ClassRegistry::init('Account');
    $account = $this->Account->findById($account_id);
    $this->Account->log($account);

    // If account doesn't exist, throw error
    if(empty($account)) {
        throw new NotFoundException(__('Account id not found: ' . $account_id));
    }

    // Call Box for folder list
    $box_url = "https://api.box.com/2.0/folders/";
    if (empty($parent_folder_id)) {
        $box_url .= "0";
    } else {
        $box_url .= $parent_folder_id;
    }
    $this->Account->log($box_url);
    $bearer = 'Bearer ' . $account['Account']['access_token'];
    $client = new Guzzle\Http\Client();

    $client->getEventDispatcher()->addListener('request.error', function(Event $event) {
        if ($event['response']->getStatusCode() == 401) {
            $Account = new Account;
            $Account->log($event);
            $Box = new BoxLib;                
            $account = $Box->refresh_token($account_id);
            $bearer = 'Bearer ' . $account['Account']['access_token'];
            $request = $client->get($box_url, array('Authorization' => $bearer));
            $event['response'] = $newResponse;

            $event->stopPropagation();
        }
    });
    $request = $client->get($box_url, array('Authorization' => $bearer));

     try {
        $response = $request->send();
     } catch (Guzzle\Http\Exception\BadResponseException $e) {
        // HTTP codes 4xx and 5xx throw BadResponseException
        $this->Account->log('Service exception!');
        $this->Account->log('Uh oh! ' . $e->getMessage());
        $this->Account->log('HTTP request URL: ' . $e->getRequest()->getUrl() . "\n");
        $this->Account->log('HTTP request: ' . $e->getRequest() . "\n");
        $this->Account->log('HTTP response status: ' . $e->getResponse()->getStatusCode() . "\n");
        $this->Account->log('HTTP response: ' . $e->getResponse() . "\n");            
     }

    $this->Account->log($response->json());
    $json = $response->json();

    $folder_list = array();
    foreach ($json['item_collection']['entries'] as $folder) {
        $folder_list[$folder['id']] = $folder['name'];
    }       
    //$this->Account->log($folder_list);

    return $folder_list;
}

`