gistfile1.rs

fn subtract(&mut self, mut other: &CountedSet<T>) {
    for (key, count) in other.iter() {
        // Data is a HashMap<T, uint>
        match self.data.find_copy(key) {
            Some(c) => { self.data.insert(*key, c - *count); }
            _ => {}
        }
    }
}