anchor.diff:  
       let mutable freeIndex = 0
       let freeList = hashSetPlus<int> HashIdentity.Structural []
  -    let stores = dictPlus<string, Store> StringComparer.Ordinal []
  +    let entityIdStore = Store<EntityId> "EntityId"
  +    let stores = Dictionary.singleton StringComparer.Ordinal "EntityId" (entityIdStore :> Store)
   
       do
           let storeTypeGeneric = typedefof<EntityId Store>
  
positive.code: 
      member this.Id = archetypeId
      member this.Length = freeIndex
      member this.Stores = stores
      member this.ComponentNames = hashSetPlus StringComparer.Ordinal stores.Keys
  
  
negative.code:         if  not (archetypes.ContainsKey archetype.Id) &&
              Subquery.evalMany archetype.Id.Terms subqueries then
              archetypes.Add (archetype.Id, archetype)
  
      member this.IndexEntitySlots ecs =
          let entities = SegmentedList.make ()
          for archetypeEntry in archetypes do
              let archetype = archetypeEntry.Value
              for i in 0 .. dec archetype.Length do
                  let entityId = archetype.EntityIdStore.[i]
                  if entityId.Active then
                      SegmentedList.add { EntityId = entityId.EntityId; Ecs = ecs } entities
          entities
  
      member this.Iterate (statement : Statement<'c, 'w>, ?compName, ?world : 'w) : 'w =
          let mutable world = Option.getOrDefault Unchecked.defaultof<'w> world
  