static protected function encode($number)
    {
        $k = self::$encoder;
        preg_match_all("/[1-9][0-9]|[0-9]/", $number, $a);
        $n = '';
        $o = count($k);
        foreach ($a[0] as $i) {
            if ($i < $o) {
                $n .= $k[$i];
            } else {
                $n .= '1' . $k[$i - $o];
            }
        }
        return $n;
    }