code: func (s *IdentityService) GetTOTP(user string) (string, error) {
  	if user == "" {
  		return "", trace.BadParameter("missing user name")
  	}
  
  	item, err := s.Get(context.TODO(), backend.Key(webPrefix, usersPrefix, user, totpPrefix))
  	if err != nil {
  		if trace.IsNotFound(err) {
  			return "", trace.NotFound("user %q is not found", user)
  		}
  		return "", trace.Wrap(err)
  	}
  
  	return string(item.Value), nil
  }
docs: // GetTOTP returns the secret key used by the TOTP algorithm to validate tokens