public function renderIndicators()
    {
        if ($this->showIndicators === false) {
            return '';
        }
        $indicators = [];
        for ($i = 0, $count = count($this->items); $i < $count; $i++) {
            $options = ['data-target' => '#' . $this->options['id'], 'data-slide-to' => $i];
            if ($i === 0) {
                Html::addCssClass($options, 'active');
            }
            $indicators[] = Html::tag('li', '', $options);
        }

        return Html::tag('ol', implode("\n", $indicators), ['class' => ['carousel-indicators']]);
    }