public function addToList($sKey, $sValue)
    {
        if (empty($sKey) || empty($sValue)) {
            return;
        }

        //Get value from storage
        $arValueList = $this->getList($sKey);

        array_unshift($arValueList, $sValue);
        $arValueList = array_unique($arValueList);

        $this->put($sKey, $arValueList);
    }