public function actionBlock($id, $back = 'index')
    {
        if ($id == \Yii::$app->user->getId()) {
            \Yii::$app->getSession()->setFlash('danger', \Yii::t('user', 'You can not block your own account'));
        } else {
            $user = $this->findModel($id);
            if ($user->getIsBlocked()) {
                $user->unblock();
                \Yii::$app->getSession()->setFlash('success', \Yii::t('user', 'User has been unblocked'));
            } else {
                $user->block();
                \Yii::$app->getSession()->setFlash('success', \Yii::t('user', 'User has been blocked'));
            }
        }
        $url = $back == 'index' ? ['index'] : ['update', 'id' => $id];
        return $this->redirect($url);
    }