anchor.diff:  
           abstract member MakeBodyShape : Entity -> BodyShape
   
  -        member this.MakeCreateBodyMessage (entity : Entity, address : Address) =
  +        member dispatcher.MakeCreateBodyMessage (entity : Entity, address : Address) =
               { EntityAddress = address
                 PhysicsId = entity.PhysicsId
                 Position = entity.Position + entity.Size * 0.5f
                 Rotation = entity.Rotation
                 BodyProperties =
  -                { Shape = this.MakeBodyShape entity
  +                { Shape = dispatcher.MakeBodyShape entity
                     BodyType = entity.BodyType
                     Density = entity.Density
                     Friction = entity.Friction
  
positive.code:     type ScreenDispatcher () =
  
          abstract member Register : Screen * Address * GroupDescriptor list * World -> World
          default this.Register (_, address, groupDescriptors, world) = World.addGroups address groupDescriptors world
  
          abstract member Unregister : Screen * Address * World -> World
          default this.Unregister (_, address, world) = World.removeGroups address world
  
      type GameDispatcher () =
          abstract member Register : Game * World -> World
          default this.Register (_, world) = world
negative.code:     type BlockDispatcher () =
          inherit Entity2dWithSimplePhysicsAndRenderingDispatcher ()
  
          override dispatcher.MakeBodyShape (block : Entity) =
              BoxShape { Extent = block.Size * 0.5f; Center = Vector2.Zero }
  
          override dispatcher.GetImageSpriteAssetName () =
              "Image3"
      
      type AvatarDispatcher () =
          inherit Entity2dWithSimplePhysicsAndRenderingDispatcher ()
          
          override dispatcher.MakeBodyShape (avatar : Entity) =
              CircleShape { Radius = avatar.Size.X * 0.5f; Center = Vector2.Zero }
  
          override dispatcher.GetImageSpriteAssetName () =
              "Image7"
  
          override dispatcher.Init (avatar, dispatcherContainer) =
  