anchor.diff:              let mutable c = 0
               for i in appendMap do
                 c <- c + 1
  -              this.AddLast(i.Key, i.Value) // TODO Add last when fixed flushing
  +              this.AddUnchecked(i.Key, i.Value) // TODO Add last when fixed flushing
               c
             else 
               let exn = SpreadsException("values overlap with existing")
  
positive.code:       finally
          exitWriteLockIf &this.state.source.locker entered
        
  
      member this.Dispose() = 
        this.state.Reset()
        if this.onUpdateHandler <> Unchecked.defaultof<_> then
          Interlocked.Decrement(&this.state.source.subscribersCounter) |> ignore
  
negative.code:             if isEqOverlap then
                let appC = appendMap.GetCursor();
                if appC.MoveAt(this.Last.Key, Lookup.GT) then
                  this.AddUnchecked(appC.CurrentKey, appC.CurrentValue) // TODO Add last when fixed flushing
                  let mutable c = 1
                  while appC.MoveNext() do
                    this.AddUnchecked(appC.CurrentKey, appC.CurrentValue) // TODO Add last when fixed flushing
                    c <- c + 1
                  c
                else 0
  