The lockfile package exports a LockFile class which provides a simple API for locking files. Unlike the Windows msvcrt.locking function, the fcntl.lockf and flock functions, and the deprecated posixfile module, the API is identical across both Unix (including Linux and Mac) and Windows platforms. The lock mechanism relies on the atomic nature of the link (on Unix) and mkdir (on Windows) system calls. An implementation based on SQLite is also provided, more as a demonstration of the possibilities it provides than as production-quality code.