Equip\Middleware\MiddlewareSet::assertValid PHP Method

    protected function assertValid(array $classes)
    {
        parent::assertValid($classes);
        foreach ($classes as $middleware) {
            if (!(is_callable($middleware) || method_exists($middleware, '__invoke'))) {
                throw MiddlewareException::notInvokable($middleware);
            }
        }
    }