Golang sets the implementation of header when it sends http requests

One day, when I needed to crawl a web page, I needed to add some information to header, so I searched 1 for how to set header in golang-initiated http requests.

package main
import (
  "fmt"
  "io/ioutil"
  "net/http"                                                                           
  "os"
  "encoding/json"
)

func main() { // generate client  Parameter is default 
  client := &http.Client{}
  // Generate the ones to access url
  url := "http://somesite/somepath/"
  // Submit a request 
  reqest, err := http.NewRequest("GET", url, nil)

  // increase header options 
  reqest.Header.Add("Cookie", "xxxxxx")
  reqest.Header.Add("User-Agent", "xxx")
  reqest.Header.Add("X-Requested-With", "xxxx")

  if err != nil {
    panic(err)
  }  
  // Processing returns results 
  response, _ := client.Do(reqest)
  defer response.Body.Close()