def _download_datasets():
    """Utility to download datasets into package source"""
    def filepath(*args):
        return abspath(join(dirname(__file__), '..', 'vega_datasets', *args))
    dataset_listing = {}
    for name in DATASETS_TO_DOWNLOAD:
        data = Dataset(name)
        url = data.url
        filename = filepath('_data', data.filename)
        print("retrieving data {0} -> {1}".format(url, filename))
        urlretrieve(url, filename)
        dataset_listing[name] = '_data/{0}'.format(data.filename)
    with open(filepath('local_datasets.json'), 'w') as f:
        json.dump(dataset_listing, f, indent=2, sort_keys=True)
Utility to download datasets into package source