protected function login()
{
$this->client->setUri($this->config['uri'] . $this->config['endpoints']['auth']);
$this->client->setParameterPost($this->config['credentials']);
$response = $this->client->request('POST');
if ($response->getStatus() > 299) {
throw new Exception('Unable to login, user credentials in config incorrect');
}
$jsonResponse = json_decode($response->getBody(), true);
$this->client->resetParameters();
$this->client->setHeaders('Authorization', 'Bearer ' . $jsonResponse['access_token']);
}