I found that `<<` can not be used by Array unless it has already been initialized. I currently write it like this:

```
unless @app
 @app = my_array
else
 @app << my_array
end 

```

Is there a better way to write this?

I used ||= before, but 

```
(@app ||= []) << [1,2,3]

```

will return [[1, 2, 3]], that's not we want. We want [1, 2, 3]