async def force_close_channel(self, chan_id: bytes) -> str:
        """Force-close the channel. Network-related exceptions are propagated to the caller.
        (automatic rebroadcasts will be scheduled)
        """
        # note: as we are async, it can take a few event loop iterations between the caller
        #       "calling us" and us getting to run, and we only set the channel state now:
        tx = self._force_close_channel(chan_id)
        await self.network.broadcast_transaction(tx)
        return tx.txid()
Force-close the channel. Network-related exceptions are propagated to the caller.
        (automatic rebroadcasts will be scheduled)
        
electrum/lnworker.py