[,ruby]
----
import mylib <1> <2> <.>
def foo
  return 42 <.> <5>
end
----
>>>
Document
  { docMeta =
      Meta
        { docTitle = []
        , docTitleAttributes = Nothing
        , docAuthors = []
        , docRevision = Nothing
        , docAttributes = fromList [ ( "sectids" , "" ) ]
        }
  , docBlocks =
      [ Block
          mempty
          Nothing
          (Listing
             (Just (Language "ruby"))
             [ SourceLine "import mylib" [ Callout 1 , Callout 2 , Callout 3 ]
             , SourceLine "def foo" []
             , SourceLine "  return 42" [ Callout 4 , Callout 5 ]
             , SourceLine "end" []
             ])
      ]
  }