class JSONUtil {

    static boolean isValidIdentifierStart( int codePoint, JSONConfig cfg )
    {
        if ( cfg.isFullJSONIdentifierCodePoints() ){
            return isValidIdentifierPart(codePoint, cfg);
        }else{
            return codePoint == '_' || codePoint == '$' ||
                    (cfg.isUseECMA6() ? Character.isUnicodeIdentifierStart(codePoint)
                                      : Character.isLetter(codePoint));
        }
    }

    private  JSONUtil();

}