anchor.diff:              match this.TryIndexSystem<'c, SystemCorrelated<'c, 'w>> () with
               | Some system -> system.UnregisterCorrelated entityId
               | None -> failwith ("Could not find expected system '" + Unchecked.defaultof<'c>.TypeName + "'.")
  +
  +        member this.UnregisterCorrelated (systemName, entityId) =
  +            match this.TryIndexSystem systemName with
  +            | Some system -> system.UnregisterComponent entityId
  +            | None -> failwith ("Could not find expected system '" + systemName + "'.")
   
           member this.SynchronizeCorrelated<'c when 'c : struct and 'c :> 'c Component> (systemNames : string HashSet) entityId =
               if systemNames.Contains Unchecked.defaultof<'c>.TypeName then
  
positive.code: 
      member this.AddNode (parentIdOpt : Guid option) =
          let nodeId = Gen.id
          let system = SystemCorrelated<'c, 'w> (buffered, ecs)
          let addedOpt =
              match parentIdOpt with
              | Some parentId ->
  
negative.code:             unregistrations.Remove entityId |> ignore<bool>
  
          // register correlation
          if registered && not isolated then
              match ecs.Correlations.TryGetValue entityId with
              | (true, correlation) ->
                  correlation.Add this.Name |> ignore<bool>
  