pub fn main(world: World) -> Void raises {
    let fs: Fs = std.fs.host()
    let created: Maybe<owned<File>> = std.fs.create(fs, ".zero/bench/zero-owned-file.txt")
    if created.has {
        var file: owned<File> = created.value
        if !std.fs.writeAll(&mut file, std.mem.span("owned file payload\n")) {
            return
        }
    }
    let opened: Maybe<owned<File>> = std.fs.open(fs, ".zero/bench/zero-owned-file.txt")
    if opened.has {
        var file: owned<File> = opened.value
        let size: Maybe<usize> = std.fs.fileLen(&mut file)
        if size.has && size.value > 0 {
            check world.out.write("owned file\n")
        }
    }
}