$client = new Client($id, $secret, ['version' => '0.3', 'error' => 'array']);
'Authorization' => 'account-bearer-token', // optional, will allow to skip login
'Redirect-URL' => 'https://your.callback.url', // must match SDK callback url
'description' => 'your-description',
'creditorName' => 'your-creditor-name',
'iban' => 'your-creditor-iban',
$response = json_encode($client->payment()->initPayment($attrs));