```ruby
test = 3 <1>
```
>>>
Document
  { docMeta =
      Meta
        { docTitle = []
        , docTitleAttributes = Nothing
        , docAuthors = []
        , docRevision = Nothing
        , docAttributes = fromList [ ( "sectids" , "" ) ]
        }
  , docBlocks =
      [ Block
          mempty
          Nothing
          (Listing
             (Just (Language "ruby")) [ SourceLine "test = 3" [ Callout 1 ] ])
      ]
  }