public function registerServices(array $serviceClosureArr) : void
    {
        foreach ($serviceClosureArr as $closure) {
            $reflection = new \ReflectionFunction($closure);
            $arguments  = $reflection->getParameters();
            if (!$closure instanceof \Closure || count($arguments) !== 1) {
                throw new \Exception(
                    "Configuration 'services' definition must be a closure"
                    ." which takes the container as its parameter and also"
                    ." returns it after configuring it."
                );
            }
            $this->container = $closure($this->container);
        }
    }