code: func (s *MemorySession) Get(key string) (interface{}, error) {
  	if value, ok := s.data[key]; ok {
  		return value, nil
  	}
  	return nil, fmt.Errorf("key %q in session (id %s) not found", key, s.sid)
  }
docs: // Get method gets the value by given a key in the session.