gistfile1.rs

    for line_or_fail in io::stdin().lines() {
        // XXX(scode): There is probably a much better way?                                                                                                                                                
        let line = line_or_fail.unwrap();
        let existed = {         
            let existing_count = line_counts.get_mut(&line);
            match existing_count {
                None => { false },
                Some(count) => { *count = *count + 1; true},
            }                          
        };   

        if !existed {
            line_counts.insert(line, 1);
        }                             
    }