anchor.diff:      KeepDuplicates : bool option
       /// There may be zero or more ItemMetadata elements in an item.
       Children : ItemMetadata list
  - }
  + }  
  +    static member empty = 
  +     {  Include        = String.Empty
  +        Exclude        = String.Empty
  +        Remove         = String.Empty
  +        Condition      = None
  +        KeepDuplicates = None
  +        KeepMetadata   = []
  +        RemoveMetadata = []
  +        Children       = []
  +     }
   
   
   /// Contains a set of user-defined Item elements. Every item used in a MSBuild 
  
positive.code:  {  Condition : Condition option
      /// Defines the inputs for the build process. There may be zero or more Item elements in an ItemGroup.
      Children : Item list
      } member private self.display =
          (StringBuilder().AppendLine(
              "Condition : " + (  if Option.isSome self.Condition 
                                  then string self.Condition.Value else ""))
  
negative.code:     /// Optional element. Contains a set of user-defined Property elements. There may be zero or 
      /// more PropertyGroup elements in an Otherwise element.
      ProperyGroupList: PropertyGroup list
   }  
      static member empty = 
       {  ChooseList       = []
          ItemGroupList    = []
          ProperyGroupList = []
       }
  
  (*
      The Choose, When, and Otherwise elements are used together to provide a way to select 
  