def get_url_and_headers_for_range(self, file_download):
        """
        Return url and headers to use for downloading part of a file, adding range headers.
        :param file_download: FileDownload: contains data about file we will download
        :return: str, dict: url to download and headers to use
        """
        headers = self.get_range_headers()
        if file_download.http_headers:
            headers.update(file_download.http_headers)
        separator = ""
        if not file_download.url.startswith("/"):
            separator = "/"
        url = '{}{}{}'.format(file_download.host, separator, file_download.url)
        return url, headers
Return url and headers to use for downloading part of a file, adding range headers.
        :param file_download: FileDownload: contains data about file we will download
        :return: str, dict: url to download and headers to use