```
    public static boolean isConstantCharacter(ByteList byteList) {
        int c, len;
        int nlen = byteList.realSize();
        Encoding enc = byteList.getEncoding();

        if (nlen < 1) return false;
        int byte0 = byteList.get(0);
        if (byte0 < 128) return enc.isUpper(byte0);

        byte[] bytes = byteList.getUnsafeBytes();
        int begin = byteList.begin();
        int end = begin + nlen;
        c = StringSupport.preciseLength(enc, bytes, begin, end);
        if (!StringSupport.MBCLEN_CHARFOUND_P(c)) return false;
        len = StringSupport.MBCLEN_CHARFOUND_LEN(c);
        c = StringSupport.codePoint(enc, bytes, begin, end);
        if (enc.isUnicode()) {
            int ctype_titlecase = 0;
            if (enc.isUpper(c)) return true;
            if (enc.isLower(c)) return false;
            if (Character.isTitleCase(c)) return true;
        }
        else {
```