$keyPair = new \Snijder\Bunq\Model\KeyPair($apiKey, $publicKey, $privateKey);
$bunqClient = new \Snijder\Bunq\BunqClient($keyPair);

$userResource = new \Snijder\Bunq\Resource\UserResource($BunqClient);
$userResource->listUsers(); //list all available users.

$bunqClient->setInstallationTokenStorage($myInstallationTokenStorage);
$bunqClient->setSessionTokenStorage($mySessionTokenStorage);

$bunqClient->setSessionTokenStorage(
    new \Snijder\Bunq\Storage\SessionTokenFileStorage($path)
);

$bunqClient->setInstallationTokenStorage(
    new \Snijder\Bunq\Storage\InstallationTokenFileStorage($path)
);