anchor.diff:          match correlations.TryGetValue entityId with
           | (true, index) ->
               if index <> freeIndex then
  -                components.[index].RefCount <- dec components.[index].RefCount
  +                components.[index].Occupied <- false
                   freeList.Enqueue index
               else freeIndex <- dec freeIndex
               true
  
positive.code: 
      member this.RemoveComponent index =
          if index <> freeIndex then
              components.[index].RefCount <- dec components.[index].RefCount
              freeList.Enqueue index
          else freeIndex <- dec freeIndex
  
  
negative.code: open Prime
  
  type Component =
      abstract Occupied : bool with get, set
  
  type [<AbstractClass>] 'w System () =
      abstract Update : 'w Ecs -> obj
  