'; echo ''; // Add other form inputs here echo ''; echo ''; // Check the submitted token against the one saved in the session if(isset($_POST['token']) && $_POST['token'] === $_SESSION['token']) { // Token is valid, process the form } else { // Token is invalid, show an error message echo 'Invalid token!'; } ?>This example generates a token using the `random_bytes` function and saves it to the session. The token is then added to a HTML form as a hidden input field. When the user submits the form, the token is checked against the one saved in the session to ensure that it is valid. The package/library used in this example is the PHP core library.