How to use the pytube.Stream function in pytube

cipher_signature.register_on_progress_callback(callback_fn)

    mocker.patch.object(request, 'get')
    request.get.side_effect = [
        {'content-length': '16384'},
        {'content-length': '16384'},
        iter([str(random.getrandbits(8 * 1024))]),
    ]
    with mock.patch('pytube.streams.open', mock.mock_open(), create=True):
        stream = cipher_signature.streams.first()
        stream.download()
    assert callback_fn.called
    args, _ = callback_fn.call_args
    assert len(args) == 4
    stream, _, _, _ = args
    assert isinstance(stream, Stream)

"""Convert manifest data to instances of :class:`Stream `.

        Take the unscrambled stream data and uses it to initialize
        instances of :class:`Stream ` for each media stream.

        :param str fmt:
            Key in stream manifest (``ytplayer_config``) containing progressive
            download or adaptive streams (e.g.: ``url_encoded_fmt_stream_map``
            or ``adaptive_fmts``).

        :rtype: None

        """
        stream_manifest = self.player_config_args[fmt]
        for stream in stream_manifest:
            video = Stream(
                stream=stream,
                player_config_args=self.player_config_args,
                monostate=self.stream_monostate,
            )
            self.fmt_streams.append(video)

"""Convert manifest data to instances of :class:`Stream `.

        Take the unscrambled stream data and uses it to initialize
        instances of :class:`Stream ` for each media stream.

        :param str fmt:
            Key in stream manifest (``ytplayer_config``) containing progressive
            download or adaptive streams (e.g.: ``url_encoded_fmt_stream_map``
            or ``adaptive_fmts``).

        :rtype: None

        """
        stream_manifest = self.player_config_args[fmt]
        for stream in stream_manifest:
            video = Stream(
                stream=stream,
                player_config_args=self.player_config_args,
                monostate=self.stream_monostate,
            )
            self.fmt_streams.append(video)

"""Convert manifest data to instances of :class:`Stream `.

		Take the unscrambled stream data and uses it to initialize
		instances of :class:`Stream ` for each media stream.

		:param str fmt:
			Key in stream manifest (``ytplayer_config``) containing progressive
			download or adaptive streams (e.g.: ``url_encoded_fmt_stream_map``
			or ``adaptive_fmts``).

		:rtype: None

		"""
		stream_manifest = self.player_config_args[fmt]
		for stream in stream_manifest:
			video = Stream(
				stream=stream,
				player_config_args=self.player_config_args,
				monostate=self.stream_monostate,
			)
			self.fmt_streams.append(video)