How to use the sshuttle.linux.nonfatal function in sshuttle

def restore_firewall(self, port, family, udp, user):
        if udp:
            raise Exception("UDP not supported by nft method_name")

        table = "nat"

        def _nft(action, *args):
            return nft(family, table, action, *args)

        chain = 'sshuttle-%s' % port

        # basic cleanup/setup of chains
        handle = nft_get_handle('chain ip nat output', chain)
        nonfatal(_nft, 'delete rule', 'output', handle)
        handle = nft_get_handle('chain ip nat prerouting', chain)
        nonfatal(_nft, 'delete rule', 'prerouting', handle)
        nonfatal(_nft, 'delete chain', chain)

def _ipm(*args):
            return ipt(family, "mangle", *args)

        chain = 'sshuttle-%s' % port

        # basic cleanup/setup of chains
        if ipt_chain_exists(family, table, chain):
            if user is not None:
                nonfatal(_ipm, '-D', 'OUTPUT', '-m', 'owner', '--uid-owner',
                         str(user), '-j', 'MARK', '--set-mark', str(port))
                args = '-m', 'mark', '--mark', str(port), '-j', chain
            else:
                args = '-j', chain
            nonfatal(_ipt, '-D', 'OUTPUT', *args)
            nonfatal(_ipt, '-D', 'PREROUTING', *args)
            nonfatal(_ipt, '-F', chain)
            _ipt('-X', chain)

return ipt_ttl(family, table, *args)

        def _ipm(*args):
            return ipt(family, "mangle", *args)

        chain = 'sshuttle-%s' % port

        # basic cleanup/setup of chains
        if ipt_chain_exists(family, table, chain):
            if user is not None:
                nonfatal(_ipm, '-D', 'OUTPUT', '-m', 'owner', '--uid-owner',
                         str(user), '-j', 'MARK', '--set-mark', str(port))
                args = '-m', 'mark', '--mark', str(port), '-j', chain
            else:
                args = '-j', chain
            nonfatal(_ipt, '-D', 'OUTPUT', *args)
            nonfatal(_ipt, '-D', 'PREROUTING', *args)
            nonfatal(_ipt, '-F', chain)
            _ipt('-X', chain)

def _ipm(*args):
            return ipt(family, "mangle", *args)

        chain = 'sshuttle-%s' % port

        # basic cleanup/setup of chains
        if ipt_chain_exists(family, table, chain):
            if user is not None:
                nonfatal(_ipm, '-D', 'OUTPUT', '-m', 'owner', '--uid-owner',
                         str(user), '-j', 'MARK', '--set-mark', str(port))
                args = '-m', 'mark', '--mark', str(port), '-j', chain
            else:
                args = '-j', chain
            nonfatal(_ipt, '-D', 'OUTPUT', *args)
            nonfatal(_ipt, '-D', 'PREROUTING', *args)
            nonfatal(_ipt, '-F', chain)
            _ipt('-X', chain)

def _ipt(*args):
            return ipt(family, table, *args)

        def _ipt_ttl(*args):
            return ipt_ttl(family, table, *args)

        def _ipm(*args):
            return ipt(family, "mangle", *args)

        chain = 'sshuttle-%s' % port

        # basic cleanup/setup of chains
        if ipt_chain_exists(family, table, chain):
            if user is not None:
                nonfatal(_ipm, '-D', 'OUTPUT', '-m', 'owner', '--uid-owner',
                         str(user), '-j', 'MARK', '--set-mark', str(port))
                args = '-m', 'mark', '--mark', str(port), '-j', chain
            else:
                args = '-j', chain
            nonfatal(_ipt, '-D', 'OUTPUT', *args)
            nonfatal(_ipt, '-D', 'PREROUTING', *args)
            nonfatal(_ipt, '-F', chain)
            _ipt('-X', chain)

def restore_firewall(self, port, family, udp, user):
        if udp:
            raise Exception("UDP not supported by nft method_name")

        table = "nat"

        def _nft(action, *args):
            return nft(family, table, action, *args)

        chain = 'sshuttle-%s' % port

        # basic cleanup/setup of chains
        handle = nft_get_handle('chain ip nat output', chain)
        nonfatal(_nft, 'delete rule', 'output', handle)
        handle = nft_get_handle('chain ip nat prerouting', chain)
        nonfatal(_nft, 'delete rule', 'prerouting', handle)
        nonfatal(_nft, 'delete chain', chain)