anchor.diff:  and [<AbstractClass>] SystemCorrelated<'t when 't : struct and 't :> Component> () =
       inherit System ()
   
  -    let correlations = dictPlus [] : Dictionary<Guid, int>
       let mutable components = [||] : 't array
       let mutable freeIndex = 0
       let freeList = Queue<int> ()
  -    member this.Components with get () = components
  -    member this.FreeIndex with get () = freeIndex
  +    let correlations = dictPlus [] : Dictionary<Guid, int>
  +    
  +    member this.Components
  +        with get () = components
  +    
  +    member this.FreeIndex
  +        with get () = freeIndex
   
       member this.GetComponent guid =
           let (found, index) = correlations.TryGetValue guid
  
positive.code:         | _ -> failwith ("Could not find expected system '" + systemName + "'.")
  
      static member addComponentCorrelated<'t when 't : struct and 't :> Component> systemName guid (comp : 't) ecs =
          match EntityComponentSystem.tryGetSystem systemName ecs with
          | Some system ->
              match system with
              | :? ('t SystemCorrelated) as systemCorr ->
  
negative.code:     abstract Active : bool with get, set
  
  type [<AbstractClass>] System () =
      abstract Update : Ecs -> obj
  
  and [<AbstractClass>] SystemSingleton<'t when 't : struct and 't :> Component> (comp : 't) =
      inherit System ()
  