protected function getRealClass($stack, $extensionNamespace)
    {
        $stackPath = \Staq\Util::convertNamespaceToPath($stack);
        $absolutePath = realpath($this->extensions[$extensionNamespace] . '/Stack/' . $stackPath . '.php');
        if (is_file($absolutePath)) {
            $realClass = $extensionNamespace . '\\Stack\\' . $stack;
            return $realClass;
        }
    }