anchor.diff:      // evaluation for a specific cell. Note that this needs to
       // be "transparent" (knowning its input) since we need to
       // be able to undo the effect.
  -    type internal LaterMod<'a>(input : IMod<'a>) as this=
  +    type internal LaterMod<'a>(input : IMod<'a>) =
           inherit LazyMod<'a>(Seq.singleton (input :> IAdaptiveObject), fun s -> input.GetValue(s))
   
           override x.Inputs = Seq.singleton (input :> IAdaptiveObject)
  
positive.code: /// By calling Reset (), the initial behaviour can be restored,
  /// i.e. the resulting value is dependent on the adaptive default
  /// value.
  type DefaultingModRef<'a>(computed : IMod<'a>) as this =
      inherit AdaptiveObject()
  
      let mutable cache = Unchecked.defaultof<'a>
  
negative.code:     // the change propagation process when equal values are
      // observed EagerMod can also be created with a custom 
      // equality function.
      type internal EagerMod<'a>(input : IMod<'a>, eq : Option<'a -> 'a -> bool>) =
          inherit LazyMod<'a>(Seq.singleton (input :> IAdaptiveObject), fun s -> input.GetValue(s))
  
          let hasChanged = ChangeTracker.trackCustom<'a> eq
  