//@ concurrently, that also reads from standard input? The result would be a mess. Hence
//@ Rust requires us to `lock` standard input if we want to perform large operations on
//@ it. (See [the documentation](https://doc.rust-lang.org/stable/std/io/struct.Stdin.html) for
- //@ more details.)
+ //@ more details.)
for line in stdin.lock().lines() {
// Rust's type for (dynamic, growable) strings is `String`. However, our variable `line`
// here is not yet of that type: It has type `io::Result<String>`.