How to re-export with pub use

Use pub use in lib.rs to re-export items from internal modules to the crate root for easier access.

Use pub use in your library crate root (src/lib.rs) to re-export an item from a module, making it available to users of your crate as if it were defined at the root.

pub mod internal {
    pub fn helper() {}
}

pub use internal::helper;

Now users can call my_crate::helper() instead of my_crate::internal::helper().