pub fn main(world: World) -> Void raises {
    let fs: Fs = std.fs.host()
    let opened: Maybe<owned<File>> = std.fs.open(fs, ".zero/conformance/std-fs-resource.txt")
    if opened.has {
        let file: owned<File> = opened.value
        var buf: [4]u8 = [0, 0, 0, 0]
        let read: i32 = std.fs.read(file, buf)
        if read.has {
            check world.out.write("unexpected read\n")
        }
    }
}