Args:
            data_dir:
                can be used to specify a manual directory to get the files from.
            dataset_name (`str`):
                name of dataset this instance will be used for. If
                provided, downloads will contain which datasets they were used for.
            download_config (`DownloadConfig`):
                to specify the cache directory and other
                download options
            base_path (`str`):
                base path that is used when relative paths are used to
                download files. This can be a remote url.
            record_checksums (`bool`, defaults to `True`):
                Whether to record the checksums of the downloaded files. If None, the value is inferred from the builder.
        """
        self._dataset_name = dataset_name
        self._data_dir = data_dir
        self._base_path = base_path or os.path.abspath(".")
        # To record what is being used: {url: {num_bytes: int, checksum: str}}