code: func RegisterEAN(pdf barcodePdf, code string) string {
  	bcode, err := ean.Encode(code)
  	return registerBarcode(pdf, bcode, err)
  }
docs: // RegisterEAN registers a barcode of type EAN to the PDF, but not to the page.
  // It will automatically detect if the barcode is EAN8 or EAN13. Use Barcode()
  // with the return value to put the barcode on the page.