anchor.diff:          _behaviors <- _behaviors @ notCompletedBehaviors
       }
   
  +    // System.IDisposable is the usual interface for disposable objects
  +    // in C#/F#. It lets you use language constructs like `use`. 
       interface IDisposable with
           member self.Dispose() =
               if not _disposed then
  
positive.code:             
      // Create our sprites
      let sprites =
          [0 .. 100]
          |> List.map (string >> createSprite texture renderer.width renderer.height)
  
      // Add sprites to stage and make some funny homing missiles
      sprites
  
negative.code:         return xs }
      |> Promise.iter(fun sprites ->
          render()
          Browser.window.requestAnimationFrame(fun dt ->
              animate sprites render dt) |> ignore)
  
  let createSprite texture stageW stageH id =
      // Behaviors
  