Another thing that should probably be clarified is that the author diagnosed the problem with the `let y = x; let z = x;` code incorrectly (assuming that Rust is creating 'bindings'), which (not having actively programmed rust for a while) greatly alarmed me because it sounds like a terrible idea. What is in fact happening is that `x`'s value is _moved_ into `y`, which is a lot easier to think about.