anchor.diff:  /// Forms a logical group of entities.
   and [<StructuralEquality; NoComparison>] Group =
       { GroupAddress : Group Address }
  +
       interface Simulant with
           member this.GetPublishingPriority _ _ = Constants.Engine.GroupPublishingPriority
           member this.SimulantAddress = Address.changeType<Group, Simulant> this.GroupAddress
  
positive.code: /// to implement things like buttons, characters, blocks, and things of that sort.
  and [<StructuralEquality; NoComparison>] Entity =
      { EntityAddress : Entity Address }
      interface Simulant with
          member this.GetPublishingPriority getEntityPublishingPriority world = getEntityPublishingPriority this world
          member this.SimulantAddress = Address.changeType<Entity, Simulant> this.EntityAddress
  
negative.code: /// currently interactive groups of entities.
  and [<StructuralEquality; NoComparison>] Screen =
      { ScreenAddress : Screen Address }
  
      interface Simulant with
          member this.GetPublishingPriority _ _ = Constants.Engine.ScreenPublishingPriority
          member this.SimulantAddress = Address.changeType<Screen, Simulant> this.ScreenAddress
  