anchor.diff:          | TagContent e ->
               { e with Annotation = Some x }
               |> TagContent
  +        | INodeContent _
           | VerbatimContent _
           | TextContent _
           | CommentContent _ -> e
  
positive.code:                         t.Contents |> Seq.collect (fun x -> x.Requires)
                          t.Attributes |> Seq.collect (fun x -> x.Requires)
                      |]
                  | _ -> Seq.empty
  
              member this.Write(meta, w) =
  
negative.code:                 Contents = el.Contents @ newContent
                  Annotation = el.Annotation
              }
          | INodeContent _
          | VerbatimContent _
          | TextContent _
          | CommentContent _ ->
  