code: func AddRoute(
  	serverType string,
  	routingFunction router.RoutingFunc,
  ) error {
  	if app.router != nil {
  		if app.running {
  			return constants.ErrChangeRouteWhileRunning
  		}
  		app.router.AddRoute(serverType, routingFunction)
  	} else {
  		return constants.ErrRouterNotInitialized
  	}
  	return nil
  }
docs: // AddRoute adds a routing function to a server type