code: func (s *IdentityService) CreateSAMLAuthRequest(req services.SAMLAuthRequest, ttl time.Duration) error {
  	if err := req.Check(); err != nil {
  		return trace.Wrap(err)
  	}
  	value, err := json.Marshal(req)
  	if err != nil {
  		return trace.Wrap(err)
  	}
  	item := backend.Item{
  		Key:     backend.Key(webPrefix, connectorsPrefix, samlPrefix, requestsPrefix, req.ID),
  		Value:   value,
  		Expires: backend.Expiry(s.Clock(), ttl),
  	}
  	_, err = s.Create(context.TODO(), item)
  	if err != nil {
  		return trace.Wrap(err)
  	}
  	return nil
  }
docs: // CreateSAMLAuthRequest creates new auth request