use BrokeYourBike\PixPayment\Client;
use BrokeYourBike\PixPayment\Interfaces\ConfigInterface;

assert($config instanceof ConfigInterface);
assert($httpClient instanceof \GuzzleHttp\ClientInterface);
assert($psrCache instanceof \Psr\SimpleCache\CacheInterface);

$apiClient = new Client($config, $httpClient, $psrCache);
$apiClient->getAuthToken();