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 index = this.GetComponentIndex entityId
          &components.[index]
  
      abstract member Register : Guid -> (string -> 'w Ecs -> 'w System) -> 'w Ecs -> int
      default this.Register entityId _ _ =
          match Dictionary.tryGetValue entityId correlations with
          | (false, _) ->
              let comp = Unchecked.defaultof<'t>
  
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>
  