JJNAPIORK / Plack-Middleware-Debug-W3CValidate-0.04 / example / good.psgi 
use strict;
use warnings;
use Plack::Builder;

builder {
    enable 'Debug', panels =>['W3CValidate'];
    sub {
        return [ 200, [ 'Content-Type' => 'text/html' ], [
            '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">', "\n",
            '<html xmlns="http://www.w3.org/1999/xhtml">',
                '<head>',
                '<title>Hello World</title>',
                '</head>',
                '<body>', 
                    '<p>Hello World</p>',
                '</body>',
            '</html>',
        ]];
    };
};