code: func UnmarshalValue(data []byte) (quad.Value, error) {
  	if len(data) == 0 {
  		return nil, nil
  	}
  	var v Value
  	if err := v.Unmarshal(data); err != nil {
  		return nil, err
  	}
  	return v.ToNative(), nil
  }
docs: // UnmarshalValue is a helper for deserialization of quad.Value.