anchor.diff:                  Contents = el.Contents @ newContent
                   Annotation = el.Annotation
               }
  +        | INodeContent _
           | VerbatimContent _
           | TextContent _
           | CommentContent _ ->
  
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:         | TextContent of string
          | VerbatimContent of string
          | CommentContent of string
          | INodeContent of INode
  
          interface INode with
  
              member this.IsAttribute =
                  match this with
                  | INodeContent n -> n.IsAttribute
                  | _ -> false
  
              member this.Requires =
                  match this with
  