public static function buttonGroup($button, $links)
    {
        foreach ($links as $key => $link) {
            $links[$key] = Html::beginTag('li')
                    . Html::a($link[0], $link[1], $link[2])
                . Html::endTag('li');
        }

        return Html::beginTag('div', ['class' => 'btn-group'])
                . Html::button($button[0], array_merge([
                    'type'=>"button",
                    'class'=>"btn btn-default dropdown-toggle",
                    'data-toggle'=>"dropdown",
                    'aria-haspopup'=>"true",
                    'aria-expanded'=>"false"
                ], $button[1]))
                . Html::beginTag('ul', ['class' => 'dropdown-menu'])
                    . implode('', $links)
                . Html::endTag('ul')
            . Html::endTag('div');
    }