code: func (s *Settings) Set(c context.Context, key string, value interface{}, who, why string) error {
  	blob, err := json.Marshal(value)
  	if err != nil {
  		return err
  	}
  	return s.storage.UpdateSetting(c, key, json.RawMessage(blob), who, why)
  }
docs: // Set changes a setting value for the given key.
  //
  // New settings will apply only when existing in-memory cache expires.
  // In particular, Get() right after Set() may still return old value.