anchor.diff:              res
   
       member x.Add(value : 'a) : bool =
  -        let value = Weak value
  +        let value = value.Weak
           if isNull set then 
               let id = pset.IndexOf(value)
               if id < 0 then 
  
positive.code:             callback ()
              false
  
  
          interface IAdaptiveObject with
              member x.Id = modId
  
negative.code:         match o with
              | :? IAdaptiveObject as o -> x.Id = id
              | _ -> false
  
      interface IWeakable<IAdaptiveObject> with
          member x.Weak =
              let w = weakThis
              if isNull w then 
                  let w = WeakReference<IAdaptiveObject>(x)
                  weakThis <- w
                  w
              else
                  weakThis
  
  
      interface IAdaptiveObject with
          member x.Id = id
  