def handle_download_click(self, *args):
        """
        Callback for download button. Downloads the file and replaces the button
        with a view of the file.
        :param args:
        :return:
        """
        self.download_button.on_click(self.handle_download_click,remove=True)
        self.download_button.description = 'Downloading ...'
        self._string = self._fileobj.read()
        self.render_string()
Callback for download button. Downloads the file and replaces the button
        with a view of the file.
        :param args:
        :return: