Yii::$app->user->isGuest ? (
                ['label' => 'Login', 'url' => ['/site/login'],
				 'label' => 'Registration', 'url' => ['/site/registration']]
            ) : (
                '<li>'
                . Html::beginForm(['/site/logout'], 'post', ['class' => 'navbar-form'])
                . Html::submitButton(
                    'Logout (' . Yii::$app->user->identity->username . ')',
                    ['class' => 'btn btn-link']
                )
                . Html::endForm()
                . '</li>'
            )