async def try_force_closing(self, chan_id):
    chan = self._channels[chan_id]
    tx = chan.force_close_tx()
    chan.set_state(ChannelState.FORCE_CLOSING)
    (await self.network.try_broadcasting(tx, 'force-close'))
async def try_force_closing(self, chan_id):
    chan = self._channels[chan_id]
    tx = chan.force_close_tx()
    chan.set_state(ChannelState.FORCE_CLOSING)
    (await self.network.try_broadcasting(tx, 'force-close'))