title: Why can child modules use private items of ancestor modules, but not the other way?
body: <p>Why can't items in a parent module use private items inside child modules, but items in child modules can use the private items in their ancestor modules?</p>
  
  <p><a href="https://doc.rust-lang.org/book/ch07-03-paths-for-referring-to-an-item-in-the-module-tree.html" rel="nofollow noreferrer">https://doc.rust-lang.org/book/ch07-03-paths-for-referring-to-an-item-in-the-module-tree.html</a></p>