Calendar scheduler doesn't compile

I am trying to build the tutorial calendar. One of the steps calls for code to be pasted into CalendarController.cs. The last paragraph looks like this:

action_type = “error”;

return View(new CalendarActionResponseModel(action_type, source_id, target_id));

I followed the directions. But the object that is unrecognized by the compiler is the CalendarActionResponseModel object in the prior line. Can anyone point me to the namespace for this or is something missing from my project?

have you defined response model as it described here:

OK I see that now. The instructions are a bit out-of-order. Thanks Aliaksandr