How to split the code into files in Rust?

Question

There are 5 files in my project. (lib.rs, one.rs, two.rs, three.rs, four.rs)

I'd like:

• lib.rs knows about one.rs, two.rs
• one.rs knows about three.rs, four.rs
• two.rs knows about three.rs, four.rs

But I can't find examples. There is a tree everywhere. I can't use tree, three.rs, four.rs must be common.