anchor.diff:          for storeEntry in stores do
               storeEntry.Value.Grow ()
   
  -    member private this.AllocIndex =
  +    member private this.AllocIndex () =
           if freeList.Count > 0 then
               let index = Seq.head freeList
               freeList.Remove index |> ignore<bool>
  
positive.code:         subscriptionId
  
      member this.Subscribe<'d, 's> event callback =
          this.SubscribePlus<'d, 's> this.SubscriptionId event callback |> ignore
  
      member this.Unsubscribe event subscriptionId =
          let result =
  
negative.code:         else freeList.Add index |> ignore<bool>
  
      member this.Register (comps : Dictionary<string, obj>) =
          let index = this.AllocIndex ()
          for compEntry in comps do
              stores.[compEntry.Key].SetItem index compEntry.Value
          index
  