任何人都可以帮我解决错误:::解析错误：语法错误，第14行/localhost/braintree/app.php中的意外T_FUNCTION

Question

<?php

require_once 'braintree-php-2.14.0/lib/Braintree.php';
require_once __DIR__ . 'silex/vendor/autoload.php';
Braintree_Configuration::environment('sandbox');
Braintree_Configuration::merchantId('...');
Braintree_Configuration::publicKey('...');
Braintree_Configuration::privateKey('...');
$app = new Silex\Application();
$app->get('/', function () {
    include 'views/form.php';
});
$app->run();
//$app->get("/braintree-php-2.14.0", function () {
$app->get("/braintree", function () {
   include 'views/response.php';
});
?>

this is braintree payments system i read the documentation clearly but not solved.error is found in this line 14: $app->get("/braintree", function () {