def METHOD_NAME(self, line: str = "", cell: str = None) -> str:
    """
    Base64 IPython magic extension.
    Parameters
    ----------
    line : str, optional
        Line contents, by default ""
    cell : str, optional
        Cell contents, by default None
    Returns
    -------
    str
        Decoded text
    """
    if cell is None:
        results, _ = base64.unpack(line)
        return results
    args = magic_arguments.parse_argstring(self.METHOD_NAME, line)
    results, df_results = base64.unpack(cell, utf16=args.utf16)
    if args.clean:
        results = re.sub(self._STRIP_TAGS, "", results)
    elif args.pretty:
        if _BS_AVAILABLE:
            xml_str = f"<decoded_string>{results}</decoded_string>"
            b_soup = BeautifulSoup(xml_str, "xml")
            results = b_soup.prettify()
    if args.out is not None:
        self.shell.user_ns[args.out] = (results, df_results)  # type: ignore
    return results