code: func certificateDirectory(server string) (string, error) {
  	u, err := url.Parse(server)
  	if err != nil {
  		return "", err
  	}
  
  	return filepath.Join(cliconfig.Dir(), "tls", u.Host), nil
  }
docs: // certificateDirectory returns the directory containing
  // TLS certificates for the given server. An error is
  // returned if there was an error parsing the server string.