mod outer {
    pub mod inner {
        pub fn public_fn() { println!("public"); }
        fn private_fn() { println!("private"); }

        pub(crate) fn crate_visible() { println!("crate visible"); }
    }

    pub fn call_inner() {
        inner::public_fn();
        inner::crate_visible();
        // inner::private_fn(); // error: function is private
    }
}

fn main() {
    outer::inner::public_fn();
    outer::inner::crate_visible();
    outer::call_inner();
}