rails/rails — pull request #7382 by KensoDev (2012-08-17 21:48:44+00:00)
Title: Adding .include method to Array

Adding the `include` method to Array
You can add an item to an array only if that item does not already exist.

```ruby
[1, 2].include(2) => [1, 2]
[1, 2].include(3) => [1, 2, 3]
```