protected function renderTools()
    {
        $tools = '';
        if($this->collapseButton !== false){
            $tools .= '<a class="collapse-link"><i class="fa fa-chevron-up"></i></a>';
        }
        if ($this->closeButton !== false) {
            $tools .= '<a class="close-link"><i class="fa fa-times"></i></a>';
        }
        if (!empty($tools)) {
            return Html::tag('div', $tools, ['class' => 'ibox-tools']);
        } else {
            return null;
        }
    }