@property
    def manual_dir(self):
        return self._data_dir

    def download(self, url_or_urls):
        """Normalize URL(s) of files to stream data from.
        This is the lazy version of `DownloadManager.download` for streaming.

        Args:
            url_or_urls (`str` or `list` or `dict`):
                URL(s) of files to stream data from. Each url is a `str`.

        Returns:
            url(s): (`str` or `list` or `dict`), URL(s) to stream data from matching the given input url_or_urls.

        Example:

        ```py
        >>> downloaded_files = dl_manager.download('https://storage.googleapis.com/seldon-datasets/sentence_polarity_v1/rt-polaritydata.tar.gz')
        ```
        """
        url_or_urls = map_nested(self._download_single, url_or_urls, map_tuple=True)
        return url_or_urls