private function determineDriver($file)
    {
        $exception = new InvalidArgumentException(
            "Cannot initialize the configuration driver. I could not determine ".
            "the correct driver class."
        );

        if (is_null($file) || !is_string($file)) {
            throw $exception;
        }

        $nameDivision = explode('.', $file);
        $extension = strtolower(end($nameDivision));

        if (!array_key_exists($extension, $this->extensionToDriver)) {
            throw $exception;
        }

        return $this->extensionToDriver[$extension];
    }