Counting request in Go

counter.go

package hello

import (
    "fmt"
    "net/http"
)

func init() {
    http.HandleFunc("/", handler)
}

var cnt uint32

func handler(w http.ResponseWriter, r *http.Request) {
    if (r.URL.Path == "/") {
        fmt.Fprintf(w, "counter: %d", cnt)
    	cnt = cnt + 1
    } else {
      	http.NotFound(w, r)
    }
}