Wordpress: child page shortcode

gistfile1

/* Child Page with Shorcode ***********************************************************************************
** http://wp.tutsplus.com/tutorials/quick-tip-display-excerpts-of-child-pages-with-a-shortcode/ ***************
** http://botcrawl.com/how-to-change-or-remove-the-howdy-greeting-message-on-the-wordpress-user-menu-bar/ ** */
/* !차일드 페이지 코드 ***************************************************************************************** */
function subpage_peek() {  
    global $post;  
    //query subpages 
    $args = array(  
        'post_parent' => $post->ID, 
        'order' => 'ASC', 
        'post_type' => 'page'  
    );  
    $subpages = new WP_query($args);  
    // create output  
    if ($subpages->have_posts()) :  
        $output = '​<div class="et-custom-list etlist-check"><ul>';  
        while ($subpages->have_posts()) : $subpages->the_post();  
            $output .= '<li><h2 style="font-size: 18px; padding-top: 5px;" class="title"><a href="'.get_permalink().'">'.get_the_title().'</a></h1> 
                        <p class="space-bottom">'.get_the_excerpt().'<br /> 
                        <a href="'.get_permalink().'">더 보기 →</a></p></li>';  
        endwhile;  
        $output .= '</ul></div>';  
    else :  
        $output = '<p>No subpages found.</p>';  
    endif;  
    // reset the query  
    wp_reset_postdata();  
    // return something  
    return $output;  
}
add_shortcode('subpage_peek', 'subpage_peek');