I am trying to create an MVC web app in golang without using any framework. How I plan to achieve it is to create an instance of a http.Server {} with a http.NewServeMux() as it's handler as coded below:

```
 sm := http.NewServeMux()
    sm.Handle("/route1", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        http.ServeFile(w, r, "static/front-office/index.html")
    }))
    sm.Handle("/route2", handleSomething())
    sm.Handle("/route3", handleSomething())
    sm.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir("static"))))

    frontEndUIServer := http.Server{
        Addr:    ":9000",
        Handler:  sm,
    }
    go frontEndUIServer.ListenAndServe()

```

then make property `sm` exportable so that any other go files can import it and create handlers on it, thereby implementing my controller. Since I am new to goLang, my question now is how do I make property `sm` exportable?