code: func NewHTTPGetter(URL, CertFile, KeyFile, CAFile string) (*HttpGetter, error) {
  	var client HttpGetter
  	tr := &http.Transport{
  		DisableCompression: true,
  		Proxy:              http.ProxyFromEnvironment,
  	}
  	if (CertFile != "" && KeyFile != "") || CAFile != "" {
  		tlsConf, err := tlsutil.NewTLSConfig(URL, CertFile, KeyFile, CAFile)
  		if err != nil {
  			return &client, fmt.Errorf("can't create TLS config: %s", err.Error())
  		}
  		tr.TLSClientConfig = tlsConf
  	}
  	client.client = &http.Client{Transport: tr}
  	return &client, nil
  }
docs: // NewHTTPGetter constructs a valid http/https client as HttpGetter