code: func (q *QRCode) Write(size int, out io.Writer) error {
  	var png []byte
  
  	png, err := q.PNG(size)
  
  	if err != nil {
  		return err
  	}
  	_, err = out.Write(png)
  	return err
  }
docs: // Write writes the QR Code as a PNG image to io.Writer.
  //
  // size is both the image width and height in pixels. If size is too small then
  // a larger image is silently written. Negative values for size cause a
  // variable sized image to be written: See the documentation for Image().