index.js
function writeLockFile(path, data, cb) { // Like fs.writeFile within a lock.
    lock(path, function (unlock) {
        fse.writeFile(path, data, function (e, d) { unlock(); cb(e, d); });
    });
}
function writeLockFile(path, data, cb) { // Like fs.writeFile within a lock.
    lock(path, function (unlock) {
        fse.writeFile(path, data, function (e, d) { unlock(); cb(e, d); });
    });
}
Should we consider using the operating system's synchronization or exclusivity utilities instead of our own locks?