code: func NewFromJSON(src []byte) (*Image, error) {
  	img := &Image{}
  
  	if err := json.Unmarshal(src, img); err != nil {
  		return nil, err
  	}
  	if img.RootFS == nil {
  		return nil, errors.New("invalid image JSON, no RootFS key")
  	}
  
  	img.rawJSON = src
  
  	return img, nil
  }
docs: // NewFromJSON creates an Image configuration from json.