How to expose method to its sibling and parent only but not to client using that crate in rust

Question

I have a library with the following structure

Cargo.toml
src
    parent_file.rs
    child_folder
        mod.r
        child_file.rs

child_folder/mod.rs

self::child_file::MyStruct;

mod child_file;

Is there anyway to block off access of method in child_file to client that is using this library but still allow parent_file to access it?