golang搭建web服务器

package mainimport ( ???"net/http" ???"fmt")func sayHelloWorld(w http.ResponseWriter, r *http.Request) { ???fmt.Fprintf(w, "Hello Wrold!") //这个写入到w的是输出到客户端的}func main() { ???http.HandleFunc("/",sayHelloWorld) ???http.ListenAndServe(":8899",nil)}