ex.go

package main

import (
    "fmt"
    "net/http"
)

type handler struct {
    shared string
}

func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "hi from handler! shared string: %s\n", h.shared)
}

func main() {
    h := &handler{shared: "gophers"}
    http.ListenAndServe(":9000", h)
}