anchor.diff:  
       member this.UpdateReferences(completeModel: Map<string,InstallModel>, usedPackages : Dictionary<string,bool>, hard) = 
           this.DeletePaketNodes("Reference")  
  -        this.DeleteEmptyReferences()
  +        
  +        ["ItemGroup";"When";"Otherwise";"Choose";"When";"Choose"]
  +        |> List.iter this.DeleteIfEmpty
   
           if hard then
               for kv in usedPackages do
  
positive.code: 
      member this.FindPaketNodes(name) = 
          [
              for node in this.Document.SelectNodes(sprintf "//ns:%s" name, this.Namespaces) do
                  let isPaketNode = ref false
                  for child in node.ChildNodes do
                          if child.Name = "Paket" then isPaketNode := true
  
negative.code:                     let firstNode = fileItemsInSameDir |> Seq.head
                      firstNode.ParentNode.InsertBefore(paketNode, firstNode) |> ignore
  
          this.DeleteIfEmpty("ItemGroup")
  
      member this.HasCustomNodes(model:InstallModel) =
          let libs = model.GetReferenceNames.Force()
  