anchor.diff:      let ofArray (a : 'a[]) =
           ConstantSet(a) :> aset<_>
   
  -    let delay (f : unit -> seq<'a>) =
  +    let delay (f : unit -> list<'a>) =
           let scope = Ag.getContext()
  -        ConstantSet(lazy (Ag.useScope scope (fun () -> f() |> Seq.toList))) :> aset<_>
  +        ConstantSet(lazy (Ag.useScope scope f)) :> aset<_>
   
       /// <summary>
       /// returns a list of all elements currently in the adaptive set. 
  
positive.code:     /// elements in the given sequence
      /// </summary>
      let ofSeq (s : seq<'a>) =
          ConstantSet(s) :> aset<_>
      
      /// <summary>
      /// creates a set containing all distinct 
  
negative.code:             delay (fun () ->
                  use r = set.GetReader()
                  r.Update(null)
                  r.Content |> Seq.toList |> List.choose f
              )
          else
              let scope = Ag.getContext()
  