How to use the js-git/helpers/serial.js function in js-git

connection.fetch(config, wrap(function (err, pack) {
  log("onfetch", err, pack);
  if (err) throw err;
  serial(
    parallel(
      repo.importRefs(pack.refs),
      repo.unpack(pack, config)
    ),
    connection.close()
  )(wrap(function (err) {
    if (err) log("FAIL", err);
    else log("DONE");
  }));
}));

}, wrap(function (err, result) {
  if (err) throw err;
  serial(
    parallel(
      repo.importRefs(result.pack.refs),
      repo.unpack(result.pack, config)
    ),
    connection.close()
  )(function (err) {
    if (err) throw err;
    log("DONE");
  });
}));

}, wrap(function (err, result) {
    if (err) throw err;
    serial(
      parallel(
        repo.importRefs(result.pack.refs),
        repo.unpack(result.pack, config)
      ),
      connection.close()
    )(function (err) {
      if (err) throw err;
      log("DONE");
    });
  }));
}