pub fn main(world: World) -> Void raises {
    let fs: Fs = std.fs.host()
    let path: String = "conformance/fixtures/std-fs-read.txt"
    let size: Maybe<usize> = std.fs.fileSize(fs, path)
    if size.has && size.value == 10 {
        check world.out.write("fs polish ok\n")
    }
}