async def sync_channel_with_watchtower(self, chan: Channel, watchtower):
    outpoint = chan.funding_outpoint.to_str()
    addr = chan.get_funding_address()
    current_ctn = chan.get_oldest_unrevoked_ctn(REMOTE)
    watchtower_ctn = (await watchtower.get_ctn(outpoint, addr))
    for ctn in range((watchtower_ctn + 1), current_ctn):
        sweeptxs = chan.create_sweeptxs(ctn)
        for tx in sweeptxs:
            (await watchtower.add_sweep_tx(outpoint, ctn, tx.inputs()[0].prevout.to_str(), tx.serialize()))
async def sync_channel_with_watchtower(self, chan: Channel, watchtower):
    outpoint = chan.funding_outpoint.to_str()
    addr = chan.get_funding_address()
    current_ctn = chan.get_oldest_unrevoked_ctn(REMOTE)
    watchtower_ctn = (await watchtower.get_ctn(outpoint, addr))
    for ctn in range((watchtower_ctn + 1), current_ctn):
        sweeptxs = chan.create_sweeptxs(ctn)
        for tx in sweeptxs:
            (await watchtower.add_sweep_tx(outpoint, ctn, tx.inputs()[0].prevout.to_str(), tx.serialize()))