public static function getRouteInstance(TheTVDbAPIInterface $parent, string $routeClassName)
    {
        if (array_key_exists($routeClassName, static::$routeInstances) === false) {
            $classImplements = class_implements($routeClassName);
            if (in_array('CanIHaveSomeCoffee\TheTVDbAPI\Route\RouteInterface', $classImplements) === false) {
                throw new InvalidArgumentException('Class does not implement the RouteInterface!');
            }
            $args = [$parent];
            static::$routeInstances[$routeClassName] = new $routeClassName(...$args);
        }
        return static::$routeInstances[$routeClassName];
    }