def get_dir_from_zipfile(zip_file, fallback=None):
    """Return the name of the root folder in a zip file.

    :param zip_file: a :class:`zipfile.ZipFile` instance.
    :param fallback: if `None`, the name of the zip file is used. This is
        returned if the zip file contains more than one top-level directory,
        or none at all.
    """
    fallback = fallback or zip_file.filename
    directories = [name for name in zip_file.namelist() if name.endswith("/")
                   and len(PurePath(name).parts) == 1]
    return fallback if len(directories) > 1 else directories[0]
def iloc(cls, dataset, index):
        import cudf

        rows, cols = index
        scalar = False
        columns = list(dataset.data.columns)
        if isinstance(cols, slice):
            cols = [d.name for d in dataset.dimensions()][cols]
        elif np.isscalar(cols):
            scalar = np.isscalar(rows)
            cols = [dataset.get_dimension(cols).name]
        else:
            cols = [dataset.get_dimension(d).name for d in index[1]]
        col_index = [columns.index(c) for c in cols]
        if np.isscalar(rows):
            rows = [rows]

        if scalar:
            return dataset.data[cols[0]].iloc[rows[0]]
        result = dataset.data.iloc[rows, col_index]

        # cuDF does not handle single rows and cols indexing correctly
        # as of cudf=0.10.0 so we have to convert Series back to DataFrame
        if isinstance(result, cudf.Series):
            if len(cols) == 1:
                result = result.to_frame(cols[0])
            else:
                result = result.to_frame().T
        return result