Documentation
//! module document
//! root as the library crate named learn_rust.
//! this can be imported from any other crate.
//! learn_rust (as binary crate) can also import this (as library crate).
#![allow(dead_code, unused_imports)]
pub mod add;
pub(crate) mod language;
pub mod math;
pub mod reexport;
mod visibility;

/// api document
pub mod mod_in_lib_direct {
    /// api document
    pub fn hello() {
        // comment
        // println!("hello");
    }
    pub mod mod_in_mod {
        // println!("hello from mod in mod");
    }
}

// lib.rs itself is a top level module, that is the crate root module.
// the namespace is `crate`