code: func Encode(content string, level RecoveryLevel, size int) ([]byte, error) {
  	var q *QRCode
  
  	q, err := New(content, level)
  
  	if err != nil {
  		return nil, err
  	}
  
  	return q.PNG(size)
  }
docs: // Encode a QR Code and return a raw PNG image.
  //
  // size is both the image width and height in pixels. If size is too small then
  // a larger image is silently returned. Negative values for size cause a
  // variable sized image to be returned: See the documentation for Image().
  //
  // To serve over HTTP, remember to send a Content-Type: image/png header.