private String doJoin(String left, String right) {
        if (left.length() == 0) {
            return right;
        }
        return left + Filesystem.SEPARATOR_STRING + right;
    }
private String doJoin ( String left , String right ) { if ( left . length ( ) == 0 ) { return right ; } return left + Filesystem . SEPARATOR_STRING + right ; }
TODO