public function get(string $identifier): \Psr\Log\LoggerInterface
    {
        if (isset($this->instances[$identifier])) {
            return $this->instances[$identifier];
        }

        if (!isset($this->configuration[$identifier])) {
            throw new \InvalidArgumentException(sprintf('The given log identifier "%s" was not configured for the "%s" factory.', htmlspecialchars($identifier), self::class), 1515355505545);
        }

        if (!class_exists(Logger::class)) {
            throw new \Exception('To use the default logging you have to have the "neos/flow-log" package installed. It seems you miss it, so install it via "composer require neos/flow-log".', 1515437383589);
        }

        $backends = $this->instantiateBackends($this->configuration[$identifier]);

        $logger = new Logger($backends);
        $this->instances[$identifier] = $logger;
        return $logger;
    }