anchor.diff:  open FSharpVSPowerTools.ProjectSystem
   
   // The tag that carries metadata about F# color-regions.
  -type DepthRegionTag(info : int * int * int * int) = 
  +type DepthRegionTag(info: int * int * int * int) = 
       interface ITag
       // why are (line,startColumn,endColumn,depth) here, and not just depth?  
       // because we might have range info for indent coloring on a blank line, and there are no chars to tag there, so we put a tag in column 0 and carry all this info as metadata
       member x.Info = info
   
  -type DepthTagger(sourceBuffer : ITextBuffer, filename : string) as self = 
  +type DepthTagger(sourceBuffer: ITextBuffer, filename: string) as self = 
       // computed periodically on a background thread
  -    let mutable results : _ [] = null
  +    let mutable results: _ [] = null
       let resultsLock = obj() // lock for reading/writing "results"
       // only updated on the UI thread in the GetTags method
  -    let mutable prevTags : ITagSpan<DepthRegionTag> [] = null
  +    let mutable prevTags: ITagSpan<DepthRegionTag> [] = null
       let mutable prevSnapshot = null
       let mutable prevResults = null
       // for the event
  
positive.code:             | _ -> ctx.Post((fun _ -> g (arg)), null))
      
      type Microsoft.FSharp.Control.Async with
          static member EitherEvent(ev1 : IObservable<'a>, ev2 : IObservable<'b>) = 
              synchronize (fun f -> 
                  Async.FromContinuations((fun (cont, _econt, _ccont) -> 
                      let rec callback1 = 
  
negative.code:                         remover2.Dispose()
                          f cont (Choice2Of2(value)))
                      
                      and remover1: IDisposable = ev1.Subscribe(callback1)
                      and remover2: IDisposable = ev2.Subscribe(callback2)
                      ())))
  
  open System
  