How to call update request using exact online API

i am using exact online PHP SDK. i am able to create record using POST Request.

How to send update request to update SalesOrder DeliveryDate using Orderid?

please find below example to update request in exact online

$salesorderline               = new \Picqer\Financials\Exact\SalesOrderLine($connection);

       $s                     = $salesorderline->find('xxxxxx-xxxx-xxx-xxxxxx');
       $s->Notes              = 'mahamood';
       $s->DeliveryDate       = '2018-08-02 08:30:00.000000';
       $s->update();