anchor.diff:          | _ -> failwith ("Could not find expected system '" + systemName + "'.")
   
       static member addComponent<'t when 't : struct and 't :> Component> systemName (comp : 't) ecs =
  -        match EntityComponentSystem.tryGetSystem systemName ecs with
  +        match Ecs.tryGetSystem systemName ecs with
           | Some system ->
               match system with
               | :? ('t SystemUncorrelated) as systemUnc -> systemUnc.AddComponent comp
  
positive.code:     abstract Active : bool with get, set
  
  type [<AbstractClass>] System () =
      abstract Update : EntityComponentSystem -> obj
  
  and [<AbstractClass>] SystemSingleton<'t when 't : struct and 't :> Component> (comp : 't) =
      inherit System ()
  
negative.code: and [<AbstractClass>] SystemCorrelated<'t when 't : struct and 't :> Component> () =
      inherit System ()
  
      let mutable components = [||] : 't array
      let mutable freeIndex = 0
      let freeList = Queue<int> ()
      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
  