WordPress – Create function for displaying admin notices

function display_admin_notice($class='updated', $message) {
 
    global $notice;
    $notice = '<div class="'.$class.'"> <p>'.$message.'</p></div>';
 
    add_action('admin_notices', function() {
        global $notice;
        echo $notice;
    });
 
}

display_admin_notice('error', 'You cannot be serious!');