public function make($key)
    {
        switch ($key) {
            case 'config': return $this->config;
            case 'em': return $this->entityManager;
            case 'extension': return $this->extensionManager;
            case 'migration': return $this->migrationManager;
            case 'log': return $this->logger;
            case 'file': return $this->files;
            default: return $this;
        }
    }