gistfile1.rs

    for line_or_fail in io::stdin().lines() {
        let entry = line_counts.entry(line_or_fail.unwrap());
        match entry {
            Occupied(mut entry) => { *entry.get_mut() = *entry.get_mut() + 1; },
            Vacant(entry) => { entry.set(1); },
        }
    }