public static function popover($content, $label, $placement = 'top', $title = null, $class = null) {
        ob_start();
        ?>
        <a href="#" class="<?= $class ?>" rel="popover" data-placement="<?= $placement ?>"
           data-content='<?= $content ?>' <?=
           $title ? ' data-original-title="' .
                   $title . '"' : ''
           ?>><?= $label ?></a>
           <?php if (self::$addPopoverJs): ?>
            <script>
                $(document).ready(function () {
                    $('a[rel="popover"]').popover({
                        html: true
                    });
                });
            </script>
            <?php
        endif;
        return ob_get_clean();
    }