code: func (m *Map) Scan(src interface{}) error {
  	b, ok := src.([]byte)
  	if !ok {
  		return errors.New("Scan source was not []byte")
  	}
  	err := json.Unmarshal(b, m)
  	if err != nil {
  		return errors.WithStack(err)
  	}
  	return nil
  }
docs: // Scan implements the sql.Scanner interface.
  // It allows to read the map from the database value.