this is totally nitpicky, but: reading the docs at https://doc.rust-lang.org/stable/book/error-handling.html it says: "Why? Because Rust will make us call unwrap! This can give us a nice bird's eye view of how we need to approach error handling." even in my web browser with "unwrap" colored, this looks really like unwrap! is a macro. Which is confusing for the learner!