phalcon flash重写输出问题~~~~~

Question

用的session模式，继承重写了session类，message前面拼了个button和一些其他字符。输出之后变成字符串，我看别人也是这么用，不用特殊处理，是什么原因？
版本3.2

比如这样子：

use Phalcon\Flash\Session as Flash;

class NewFlash extends Flash
{
    public function __construct($cssClasses = null)
    {
        if ($cssClasses === null) {
            $cssClasses = array(
                'success' => 'alert alert-success',
                'notice'  => 'alert alert-info',
                'warning' => 'alert alert-warning',
                'error'   => 'alert alert-danger',
            );
        }
        parent::__construct($cssClasses);
    }

    public function message($type, $message)
    {

        $msg = "<button type=\"button\" class=\"close\" data-dismiss=\"alert\" aria-hidden=\"true\">&times;</button>
                    <h4><i class=\"icon fa fa-ban\"></i>提示</h4>";
        $msg = $button.$msg;
        parent::message($type, $msg);
    }

    public function output($remove = true)
    {
        parent::output($remove);
    }
}