code: func Unmarshal(data []byte) (interface{}, error) {
  	var msg map[string]interface{}
  	err := json.Unmarshal(data, &msg)
  	if err != nil {
  		log.Errorf("json.Unmarshal failed: %+v", err)
  		return nil, err
  	}
  	return msg, nil
  }
docs: // Unmarshal message from byte array.