public function rewriteNamespacedImports (string $fileContent) : string
    {
        $importParser = new CssUrlImportParser();
        return $importParser->replaceValidImports(
            $fileContent,
            function (string $path)
            {
                try
                {
                    $asset = Asset::createFromAssetPath($path);
                    return $this->assetUrl->generateUrl($asset);
                }
                catch (AssetsException $e)
                {
                    // wasn't an asset path
                    return $path;
                }
            }
        );
    }