code: func devTLSConfigFromFiles(caFile, certFile,
  	keyFile string) (*tls.Config, error) {
  
  	roots := x509.NewCertPool()
  
  	bs, err := ioutil.ReadFile(caFile)
  	if err != nil {
  		return nil, err
  	}
  
  	roots.AppendCertsFromPEM(bs)
  
  	cert, err := tls.LoadX509KeyPair(certFile, keyFile)
  	if err != nil {
  		return nil, err
  	}
  
  	cfg := defaultTLSConfig()
  	cfg.Certificates = []tls.Certificate{cert}
  	cfg.RootCAs = roots
  	cfg.ClientCAs = roots
  
  	return cfg, nil
  }
docs: // devTLSConfigFromFiles returns a default TLS Config but with certs and CAs
  // based on local files for dev. No verification is setup.