add(function ($req, $res, $next) { return 'Not a response'; }); return $middleware; } /** * @param \Psr\Http\Message\ServerRequestInterface $request The request * @param \Psr\Http\Message\ResponseInterface $request The response * @param callable $next The next middleware * @return \Psr\Http\Message\ResponseInterface */ public function __invoke(ServerRequestInterface $request, ResponseInterface $response, $next) { return $res; } }