public function getServicesByTag($tag, $forceType = null)
    {
        $services = [];
        foreach ($this->taggedServices->key($tag, [], true) as $serviceName) {
            $service = $this->getService($serviceName);
            if (!$this->isNull($forceType) && !$this->isInstanceOf($service, $forceType)) {
                continue;
            }
            $services[$serviceName] = $service;
        }

        return $services;
    }