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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def open_session(self, protocol_factory, peer_jid, *, stanza_type=ibb_xso.IBBStanzaType.IQ, block_size=4096, sid=None):
 """ Establish an in-band bytestream session with `peer_jid` and return the transport and protocol. :param protocol_factory: the protocol factory :type protocol_factory: a nullary callable returning an :class:`asyncio.Protocol` instance :param peer_jid: the JID with which to establish the byte-stream. :type peer_jid: :class:`aioxmpp.JID` :param stanza_type: the stanza type to use :type stanza_type: class:`~aioxmpp.ibb.IBBStanzaType` :param block_size: the maximal size of blocks to transfer :type block_size: :class:`int` :param sid: the session id to use :type sid: :class:`str` (must be a valid NMTOKEN) :returns: the transport and protocol :rtype: a tuple of :class:`aioxmpp.ibb.service.IBBTransport` and :class:`asyncio.Protocol` """

        if block_size > MAX_BLOCK_SIZE:
            raise ValueError("block_size too large")

        if sid is None:
            sid = utils.to_nmtoken(random.getrandbits(8*8))
        open_ = ibb_xso.Open()
        open_.stanza = stanza_type
        open_.sid = sid
        open_.block_size = block_size

        # XXX: retry on XMPPModifyError with RESOURCE_CONSTRAINT
        yield from self.client.send(
            aioxmpp.IQ(
                aioxmpp.IQType.SET,
                to=peer_jid,
                payload=open_,
            )
        )

        handle = self._sessions[sid, peer_jid] = IBBTransport(
            self,
            peer_jid,
            sid,
            stanza_type,
            block_size,
        )

        protocol = protocol_factory()
        handle.set_protocol(protocol)
        return handle, protocol