How to use the kipoi.external.torchvision.dataset_utils.download_url function in kipoi

# Get the metadata features
        if cell_line is None:
            if RNAseq_PC_file is None:
                raise ValueError("RNAseq_PC_file has to be specified when cell_line=None")
            assert os.path.exists(RNAseq_PC_file)
        else:
            # Using the pre-defined cell-line
            output_dir = os.path.join(this_dir, "../../template/downloaded/dataloader_files/RNAseq_features/")
            makedir_exist_ok(output_dir)
            RNAseq_PC_file = os.path.join(output_dir, cell_line, "meta.txt")
            url_template = ('https://s3.eu-central-1.amazonaws.com/kipoi-models/dataloader_files/'
                            'FactorNet/dataloader_files/RNAseq_features/{}/meta.txt')
            # rf = RemoteFile(url=url_template.format(cell_line))
            if not os.path.exists(RNAseq_PC_file):  # or not rf.validate(mappability_file):
                # download the path
                download_url(url_template.format(cell_line), os.path.join(output_dir, cell_line), "meta.txt")
                # rf.get_file(RNAseq_PC_file)

        self.meta_feat = pd.read_csv(RNAseq_PC_file,
                                     sep="\t", header=None)[0].values