Contao\TemplateInheritance::insert PHP Method

    public function insert($name, array $data = null)
    {
        /** @var Template $tpl */
        if ($this instanceof Template) {
            $tpl = new static($name);
        } elseif (TL_MODE == 'BE') {
            $tpl = new \BackendTemplate($name);
        } else {
            $tpl = new \FrontendTemplate($name);
        }
        if ($data !== null) {
            $tpl->setData($data);
        }
        echo $tpl->parse();
    }