如何使用同级/相邻rust文件中的结构?

我正在尝试编辑具有以下结构的Rust项目:

src/iface/ip.rs

src/iface/tun.rs

I want to call things from ip.rs inside tun.rs. So on tun.rs I added:

use iface::ip;

但它说

unresolved import `iface::ip`

no `ip` in `iface`rustc(E0432)

This seems to be the way to do it as explained here https://stackoverflow.com/a/30687811/6655884 and here https://stackoverflow.com/a/26390046/6655884

I also tried mod ip but it didn't work either.