code: func NewImageBlock(imageURL, altText, blockID string, title *TextBlockObject) *ImageBlock {
  	return &ImageBlock{
  		Type:     mbtImage,
  		ImageURL: imageURL,
  		AltText:  altText,
  		BlockID:  blockID,
  		Title:    title,
  	}
  }
docs: // NewImageBlock returns an instance of a new Image Block type