public function asset($uri = null)
    {
        if (empty($uri)) {
            // Allow empty
        } elseif (substr($uri, 0, 7) == "http://"
            || substr($uri, 0, 8) == "https://"
            || substr($uri, 0, 2) == "//"
        ) {
            // Fully qualified, just leave as is.
            return rtrim($uri, '/');
        } elseif ($uri[0] == '/') {
            // Absolute url, prepend with staticSiteUrl
            return rtrim($this->staticSiteUrl . rtrim($uri, '/'), '/');
        }

        $baseUrl = isset($this->staticBaseUrl)
            ? $this->staticBaseUrl
            : $this->baseUrl;

        return empty($uri)
            ? $baseUrl
            : $baseUrl . '/' . $uri;
    }