/** @internal */
public function __construct($apiKey, $apiSecret, $options = array())
{
// unpack optional arguments (merging with default values) into named variables
$defaults = array('apiUrl' => 'https://api.opentok.com', 'client' => null);
$options = array_merge($defaults, array_intersect_key($options, $defaults));
list($apiUrl, $client) = array_values($options);
// validate arguments
Validators::validateApiKey($apiKey);
Validators::validateApiSecret($apiSecret);
Validators::validateApiUrl($apiUrl);
Validators::validateClient($client);
$this->client = isset($client) ? $client : new Client();
$this->client->configure($apiKey, $apiSecret, $apiUrl);
$this->apiKey = $apiKey;
$this->apiSecret = $apiSecret;
}