anchor.diff:              and set value = this.RefCount <- value
       member this.Components
           with get () = this.Entries.Values :> 't Simplex IEnumerable
  -    member this.RegisterComponent (multiId, comp) =
  +    member this.RegisterMultiplexed (multiId, comp) =
           this.Entries.Add (multiId, { Simplex = comp })
  -    member this.UnregisterComponent multiId =
  +    member this.UnregisterMultiplexed multiId =
           this.Entries.Remove multiId
   
   /// A base system type of an Ecs.
  
positive.code: 
      type 'w Ecs with
  
          member this.QualifyCorrelated<'t when 't : struct and 't :> Component> systemName entityId =
              let systemOpt = this.TryIndexSystem<SystemCorrelated<'t, 'w>> systemName
              if Option.isNone systemOpt then failwith ("Could not find expected system '" + systemName + "'.")
              let system = Option.get systemOpt
              system.HasComponent entityId
  
          member this.IndexCorrelated<'t when 't : struct and 't :> Component> systemName entityId =
              let systemOpt = this.TryIndexSystem<SystemCorrelated<'t, 'w>> systemName
              if Option.isNone systemOpt then failwith ("Could not find expected system '" + systemName + "'.")
              let system = Option.get systemOpt
              &system.GetComponent entityId
  
          member this.RegisterCorrelated<'t when 't : struct and 't :> Component> systemName entityId comp =
              match this.TryIndexSystem<SystemCorrelated<'t, 'w>> systemName with
  
negative.code:             match this.TryIndexSystem<SystemCorrelated<'t, 'w>> systemName with
              | Some system ->
                  if system.UnregisterCorrelated entityId this then
                      match this.Correlations.TryGetValue entityId with
                      | (true, correlation) -> correlation.Add systemName
                      | (false, _) -> this.Correlations.Add (entityId, List [systemName])
  