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:                 query.RegisterArchetype archetype
          archetype
  
      member private this.SubscriptionId =
          subscriptionIdCurrent <- inc subscriptionIdCurrent
          if subscriptionIdCurrent = UInt32.MaxValue then failwith "Unbounded use of ECS subscription ids not supported."
          subscriptionIdCurrent
  
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
  