anchor.diff:  
       let mutable components = ArrayRef<'c>.make reserve
       let mutable freeIndex = 0
  +    let preList = HashSet<int> ()
       let freeList = HashSet<int> ()
  -    let preDeque = HashSet<int> ()
       let correlations = dictPlus [] : Dictionary<Guid, int>
       let correlationsBack = dictPlus [] : Dictionary<int, Guid>
   
  
positive.code: 
      member this.Components with get () = components
      member this.FreeIndex with get () = freeIndex and internal set value = freeIndex <- value
      member internal this.FreeList with get () = freeList
      member internal this.PreDeque with get () = preDeque
      member internal this.Correlations with get () = correlations
      member internal this.CorrelationsBack with get () = correlationsBack
  
  
negative.code:                         components.Array.[index] <- comp
                          correlations.Add (entityId, index)
                          correlationsBack.Add (index, entityId)
                      else preList.Add index |> ignore
  
                  // fin
                  entityId
  