Rust 1.33.0

# Comments

There is a new edition of the book and this is an old link.

> Comments must start with two slashes and continue until the end of the line. For comments that extend beyond a single line, you’ll need to include // on each line.

    // So we’re doing something complicated here, long enough that we need
    // multiple lines of comments to do it! Whew! Hopefully, this comment will
    // explain what’s going on.Run

Here are the relevant sections in the new and old books:

- in the current edition: Ch 3.04 — Comments
- In the first edition: Ch 3.4 — Comments