anchor.diff:      abstract Active : bool with get, set
   
   type [<AbstractClass>] System () =
  -    abstract Update : EntityComponentSystem -> obj
  +    abstract Update : Ecs -> obj
   
   and [<AbstractClass>] SystemSingleton<'t when 't : struct and 't :> Component> (comp : 't) =
       inherit System ()
  
positive.code:         | _ -> 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
          | Some system ->
              match system with
              | :? ('t SystemUncorrelated) as systemUnc -> systemUnc.AddComponent comp
  
negative.code:             true
          | (false, _) -> false
  
  /// NOTE: Uncorrelated systems can update in parallel.
  and [<NoEquality; NoComparison>] Ecs =
      { Systems : Dictionary<string, System>
        Correlations : Dictionary<Guid, string List> }
  
  