docs: public static byte[] decodeChecked(String input) {
        byte tmp[] = decode(input);
        if (tmp == null || tmp.length < 4) {
           return null;
        }
        byte[] bytes = copyOfRange(tmp, 0, tmp.length - 4);
        byte[] checksum = copyOfRange(tmp, tmp.length - 4, tmp.length);
  
        tmp = HashUtils.doubleSha256(bytes);
        byte[] hash = copyOfRange(tmp, 0, 4);
        if (!Arrays.equals(checksum, hash)) {
           return null;
        }
  
        return bytes;
     }