anchor.diff:                          (InstallModel.EmptyModel("",SemVer.Parse "0"))
   
           let chooseNode = this.GenerateXml(merged.FilterFallbacks())
  -        
  -        match this.Document.SelectNodes("//ns:Project/ns:ItemGroup", this.Namespaces) |> Seq.cast<XmlNode> |> Seq.firstOrDefault with
  +
  +        match this.ProjectNode |> getNodes "ItemGroup" |> Seq.firstOrDefault with
           | None -> this.ProjectNode.AppendChild(chooseNode) |> ignore
           | Some firstNode -> firstNode.ParentNode.InsertBefore(chooseNode,firstNode) |> ignore
                   
  
positive.code:         let libs = model.GetReferenceNames.Force()
          
          let hasCustom = ref false
          for node in this.Document.SelectNodes("//ns:Reference", this.Namespaces) do
              if Set.contains (node.Attributes.["Include"].InnerText.Split(',').[0]) libs then
                  let isPaket = ref false
                  for child in node.ChildNodes do
  
negative.code:         let nodesToDelete = List<_>()
          
          let libs = model.GetReferenceNames.Force()
          for node in this.Document |> getDescendants "Reference" do
              if Set.contains (node.Attributes.["Include"].InnerText.Split(',').[0]) libs then          
                  nodesToDelete.Add node
  
  