How to use the sshuttle.helpers.log function in sshuttle

def test_log(mock_stderr, mock_stdout):
    sshuttle.helpers.log("message")
    sshuttle.helpers.log("abc")
    sshuttle.helpers.log("message 1\n")
    sshuttle.helpers.log("message 2\nline2\nline3\n")
    sshuttle.helpers.log("message 3\nline2\nline3")
    assert mock_stdout.mock_calls == [
        call.flush(),
        call.flush(),
        call.flush(),
        call.flush(),
        call.flush(),
    ]
    assert mock_stderr.mock_calls == [
        call.write('prefix: message'),
        call.flush(),
        call.write('prefix: abc'),
        call.flush(),
        call.write('prefix: message 1\n'),
        call.flush(),

def test_log(mock_stderr, mock_stdout):
    sshuttle.helpers.log("message")
    sshuttle.helpers.log("abc")
    sshuttle.helpers.log("message 1\n")
    sshuttle.helpers.log("message 2\nline2\nline3\n")
    sshuttle.helpers.log("message 3\nline2\nline3")
    assert mock_stdout.mock_calls == [
        call.flush(),
        call.flush(),
        call.flush(),
        call.flush(),
        call.flush(),
    ]
    assert mock_stderr.mock_calls == [
        call.write('prefix: message'),
        call.flush(),
        call.write('prefix: abc'),
        call.flush(),
        call.write('prefix: message 1\n'),
        call.flush(),
        call.write('prefix: message 2\n'),
        call.write('---> line2\n'),

def main():
    opt = parser.parse_args()

    if opt.sudoers or opt.sudoers_no_modify:
        if platform.platform().startswith('OpenBSD'):
            log('Automatic sudoers does not work on BSD')
            exit(1)

        if not opt.sudoers_filename:
            log('--sudoers-file must be set or omited.')
            exit(1)

        sudoers(
            user_name=opt.sudoers_user,
            no_modify=opt.sudoers_no_modify,
            file_name=opt.sudoers_filename
        )

    if opt.daemon:
        opt.syslog = 1
    if opt.wrap:
        import sshuttle.ssnet as ssnet

opt.method,
                                      sh,
                                      opt.auto_hosts,
                                      opt.auto_nets,
                                      includes,
                                      excludes,
                                      opt.daemon,
                                      opt.to_ns,
                                      opt.pidfile,
                                      opt.user,
                                      opt.sudo_pythonpath)

            if return_code == 0:
                log('Normal exit code, exiting...')
            else:
                log('Abnormal exit code %d detected, failing...' % return_code)
            return return_code

    except Fatal as e:
        log('fatal: %s\n' % e)
        return 99
    except KeyboardInterrupt:
        log('\n')
        log('Keyboard interrupt: exiting.\n')
        return 1

opt.dns,
                                      nslist,
                                      opt.method,
                                      sh,
                                      opt.auto_hosts,
                                      opt.auto_nets,
                                      includes,
                                      excludes,
                                      opt.daemon,
                                      opt.to_ns,
                                      opt.pidfile,
                                      opt.user,
                                      opt.sudo_pythonpath)

            if return_code == 0:
                log('Normal exit code, exiting...')
            else:
                log('Abnormal exit code %d detected, failing...' % return_code)
            return return_code

    except Fatal as e:
        log('fatal: %s\n' % e)
        return 99
    except KeyboardInterrupt:
        log('\n')
        log('Keyboard interrupt: exiting.\n')
        return 1

def list_routes():
    if which('ip'):
        routes = _list_routes(['ip', 'route'], _route_iproute)
    elif which('netstat'):
        routes = _list_routes(['netstat', '-rn'], _route_netstat)
    else:
        log('WARNING: Neither ip nor netstat were found on the server.\n')
        routes = []

    for (family, ip, width) in routes:
        if not ip.startswith('0.') and not ip.startswith('127.'):
            yield (family, ip, width)

def callback(self, sock):
        log('--no callback defined-- %r\n' % self)
        (r, _, _) = select.select(self.socks, [], [], 0)
        for s in r:
            v = s.recv(4096)
            if not v:
                log('--closed-- %r\n' % self)
                self.socks = []
                self.ok = False

finally:
                _extra_fd = os.open(os.devnull, os.O_RDONLY)
            return
        else:
            raise

    dstip = method.get_tcp_dstip(sock)
    debug1('Accept TCP: %s:%r -> %s:%r.\n' % (srcip[0], srcip[1],
                                              dstip[0], dstip[1]))
    if dstip[1] == sock.getsockname()[1] and islocal(dstip[0], sock.family):
        debug1("-- ignored: that's my address!\n")
        sock.close()
        return
    chan = mux.next_channel()
    if not chan:
        log('warning: too many open channels.  Discarded connection.\n')
        sock.close()
        return
    mux.send(chan, ssnet.CMD_TCP_CONNECT, b'%d,%s,%d' %
             (sock.family, dstip[0].encode("ASCII"), dstip[1]))
    outwrap = MuxWrapper(mux, chan)
    handlers.append(Proxy(SockWrapper(sock, sock), outwrap))
    expire_connections(time.time(), mux)

opt.pidfile,
                                      opt.user,
                                      opt.sudo_pythonpath)

            if return_code == 0:
                log('Normal exit code, exiting...')
            else:
                log('Abnormal exit code %d detected, failing...' % return_code)
            return return_code

    except Fatal as e:
        log('fatal: %s\n' % e)
        return 99
    except KeyboardInterrupt:
        log('\n')
        log('Keyboard interrupt: exiting.\n')
        return 1