Expand description
Organize code into modules.
Use mod to create new modules to encapsulate code, including other
modules:
mod foo {
    mod bar {
        type MyType = (u8, u8);
        fn baz() {}
    }
}Like structs and enums, a module and its content are private by
default, inaccessible to code outside of the module.
To learn more about allowing access, see the documentation for the pub
keyword.