我为自定义post类型查询创建了一个快捷码，但当我向其中添加meta\\u查询值时，它会抛出一个错误：

Notice: Undefined variable: my in E:\\xampp\\htdocs\\test\\wp-content\\themes\\test-theme\\functions.php on line 182

function list_unit( $atts ) {
    $args = array( 
        \'post_type\' => \'unit\',
        \'posts_per_page\' => -1,
        \'post_parent\' => \'0\',
        \'orderby\' => \'menu_order\',
        \'meta_query\' => array(
                    array(
                        \'key\' => \'first_item_key\', 
                        \'value\' => \'false\',
                        \'compare\' => \'=\'
                    )
        ),

    );

    $the_query = new WP_Query( $args );

    if ( $the_query->have_posts() ) {
        $my = \'<table>\';
        while ( $the_query->have_posts() ) {
            $the_query->the_post();
            $my .= \'<tr><td><a href="\'. get_the_permalink() .\'">\'; 
            $my .=  get_the_title() ; 
            $my .= \'</a></td></tr>\';
        }
        $my .= \'</table>\';
    } else {
        // no posts found
    }

    return $my;

}
add_shortcode( \'unit\', \'list_unit\' );