public function message($str)
 {
     $ret = "\n";
     $ret .= ReceiptLib::biggerFont(ReceiptLib::centerBig('Save $5 on a ')) . "\n";
     $ret .= ReceiptLib::biggerFont(ReceiptLib::centerBig('purchase of $25 or more')) . "\n\n";
     $expires = strtotime('+30 days');
     $ret .= ReceiptLib::centerString('Expires: ' . date('m/d/Y', $expires)) . "\n";
     $barcode = 'RC' . date('ym', $expires) . '009';
     $ret .= ReceiptLib::code39($barcode);
     return array('print' => $ret, 'any' => '');
 }