= 5.4.0 required'); } function requireDependencies() { $requiredExtensions = ['xmlwriter', 'openssl', 'dom', 'hash', 'curl']; foreach ($requiredExtensions AS $ext) { if (!extension_loaded($ext)) { throw new Braintree_Exception('The Braintree library requires the ' . $ext . ' extension.'); } } } requireDependencies();