Later we use this method (add) as:

```ruby
puts "[#{movie.title}] is already on your list!" unless movie_list.add(movie)
```

This means this method is responsible for two things:

0. keeping the movies unique (prevent dupes)
0. telling you if the movie was a dupe

There are exceptions to this rule, but I think Command/Query separation is a good one to follow. More: http://martinfowler.com/bliki/CommandQuerySeparation.html & http://tony.pitluga.com/2011/08/04/command-query-separation-in-ruby.html

In this specific case, I might add a "contains?" method

```ruby
if movie_list.contains? movie
  puts "[#{movie.title}] is already on your list!"
else
  movie_list.add movie
end
```

thoughts? what do you think?