code: func HttpGetBytes(client *http.Client, url string, header http.Header) ([]byte, error) {
  	rc, err := HttpGet(client, url, header)
  	if err != nil {
  		return nil, err
  	}
  	defer rc.Close()
  	return ioutil.ReadAll(rc)
  }
docs: // HttpGetBytes gets the specified resource. ErrNotFound is returned if the server
  // responds with status 404.