anchor.diff:              | _ -> failwith ("Could not find expected system '" + systemName + "' of required type.")
           | _ -> failwith ("Could not find expected system '" + systemName + "'.")
   
  -    let queryEntity<'t, 'w when 't : struct and 't :> Component> systemName entityId ecs =
  +    let checkEntity<'t, 'w when 't : struct and 't :> Component> systemName entityId ecs =
           let systemOpt = tryGetSystem systemName ecs
           if Option.isNone systemOpt then failwith ("Could not find expected system '" + systemName + "'.")
           let system = Option.get systemOpt
  
positive.code: 
      let mutable junctionsOpt = None : Dictionary<string, 'w System> option
  
      member this.GetJunctions getSystem (ecs : 'w Ecs) =
          match junctionsOpt with
          | Some junctions -> junctions
          | None ->
              let junctions = junctionedSystemNames |> Array.map (fun sourceName -> (sourceName, getSystem sourceName ecs)) |> dictPlus
              junctionsOpt <- Some junctions
              junctions
  
      override this.Register entityId getSystem ecs =
          match Dictionary.tryGetValue entityId this.Correlations with
          | (false, _) ->
              let junctions = this.GetJunctions getSystem ecs
              let comp = this.Junction junctions entityId ecs
              if this.FreeList.Count = 0 then
                  if this.FreeIndex < this.Components.Length - 1 then
  
negative.code:         (entityId : Guid)
          (ecs : 'w Ecs) =
          let system = junctions.[typeof<'t>.Name] :?> SystemCorrelated<'t, 'w>
          let index = system.Register entityId ecs
          ComponentRef.make index system.Components
  
      let disjunction<'t, 'w when 't : struct and 't :> Component>
  