session_start(); // do some processing here... if ($success) { // set the success message in the session sessionMessage('Your action was successful!', 'success'); } else { // set the error message in the session sessionMessage('There was an error in the action!', 'error'); } // redirect the user to a new page header('Location: /path/to/new/page.php'); exit();In this example, the `session_start()` function is called to initiate a session. The `sessionMessage()` function is then used to set a message in the session, depending on whether the action was successful or not. Finally, the user is redirected to a new page. The package/library that might contain the sessionMessage function could be a utility library for PHP web development or a more comprehensive PHP framework such as Laravel or Symfony.