Google Checkout c# - get notifications from a notification serial-number

Question

Hi - I am using GCheckout. I am receiving notifications that contain just the serial-number. I would like to use that serial-number to get a list of events that I can then process. Something like this:

var serial-number = Request["serial-number"].ToString();

var eventsRequester = new EventsRequester();

var events = eventsRequester.GetEvents(serial-number);

I don't know the name of the class that would substitute for EventsRequester.

Any thoughts?