public function getstr($key, $params=[], $alternative=null, $lang=null){

        if (!$lang) {
            $lang = $this->locale;
        }

        if (!$alternative){
            $alternative = $key;
        }

        return \vsprintf(isset($this->_languages[$lang][$key]) ? $this->_languages[$lang][$key]:$alternative, $params);
    }