So here are some things the book chapter misses that are source of confusion elsewhere in this thread - `extern crate` is logically a crate-internal magic `pub

So here are some things the book chapter misses that are source of confusion elsewhere in this thread - `extern crate` is logically a crate-internal magic `pub mod` or `pub use` - You should usually put your `extern crate`s in the crate root - Putting these two together, you can refer to crates as if they were toplevel modules. This is one of the very common confusions I've seen.