Klarna provides a number of different callbacks during the customer'scheckout session. The callbacks can be used to update the order when thecustomer changes their address as well as to do a final check to validatethe order before it is submitted. The callbacks are sent as POST requeststo the endpoint you specify when creating the order. Your response isinterpreted using the response code and body. Read more on[here](https://docs.klarna.com/kco/).