anchor.diff:                      | None ->
                           ()
   
  +    member x.Chaperone = getChaperone()
  +
       member x.BackgroundColor
           with get() = backgroundColor
           and set c = backgroundColor <- c
  
positive.code: 
  
      [<VolatileField>]
      let mutable isAlive = true
  
      let check (str : string) (err : EVRCompositorError) =
          if err <> EVRCompositorError.None then
  
negative.code:     let mutable frameCount = 0
      let mutable statFrameCount = 20
      let evtStatistics = EventSource<VrSystemStats>()
  
      let mutable textures = None
  
      static member EyeIndexSym = sEyeIndex
      static member RCoordSym = sRCoord
  