anchor.diff:              let name = Gen.nameIf nameOpt
               (id, name)
   
  +        /// Allocate a unique int.
  +        static member alloc () =
  +            if UniquesFree.Count = 0 then
  +                if UniqueCeiling = Int32.MaxValue then failwith "No unique ints available - likely due to resource leak."
  +                let unique = UniqueCeiling
  +                UniqueCeiling <- inc UniqueCeiling
  +                unique
  +            else
  +                let unique = Seq.head UniquesFree
  +                UniquesFree.Remove unique |> ignore
  +                unique
  +
  +        /// Free a unique int.
  +        static member free unique =
  +            UniquesFree.Add unique
  +
   /// Generates engine-specific values on-demand.
   type Gen = Gen.Gen
positive.code: 
  namespace Nu
  open System
  open System.Text
  open Prime
  
  
negative.code:     let private Cids = dictPlus<string, Guid> StringComparer.Ordinal []
      let private CidBytes = Array.zeroCreate 16
      let private CnameBytes = Array.zeroCreate 16
      let mutable private UniqueCeiling = System.Int32.MinValue
      let private UniquesFree = HashSet ()
  
      /// Generates engine-specific values on-demand.
      type Gen =
  