A closure that responds to or forwards a Request.
If this instance does not respond to a request, this closure is invoked, passing in the Request being processed. This is the barebones handler for RequestController.
This closure must return a Request or Response.
This method returns a RequestController that further RequestControllers can be chained to.
Source
RequestController listen(
Future<RequestOrResponse> requestControllerFunction(
Request request)) {
var controller = new RequestController()
.._listener = requestControllerFunction;
this.nextController = controller;
return controller;
}