I like Zig and I like their approach in this case.

From the article:

    std.Io.Threaded - based on a thread pool.

      -fno-single-threaded - supports concurrency and cancellation.
      -fsingle-threaded - does not support concurrency or cancellation.

    std.Io.Evented - work-in-progress [...]

Should `std.Io.Threaded` not be split into `std.Io.Threaded` and `std.Io.Sequential` instead? Single threaded is another word for "not threaded", or am I wrong here?