anchor.diff:                  cursor.Dispose()
                   new BatchMapValuesCursor<_,_,_>(cursorFactory, f2) :> ICursor<_,_>
                 ) :> Series<_,_>
  -
   
   
   and
  
positive.code:       member this.SyncRoot with get() = this.SyncRoot
  
        member this.IsEmpty = this.IsEmpty
        //member this.Count with get() = map.Count
        member this.First with get() = this.First 
        member this.Last with get() = this.Last
        member this.TryFind(k:'K, direction:Lookup, [<Out>] result: byref<KeyValuePair<'K, 'V>>) = this.TryFind(k, direction, &result)
  
negative.code:     [<DefaultValueAttribute>]
      val mutable internal subscribersCounter : int
      do
        this.onUpdateEvent <- new EventV2<OnUpdateHandler,bool>()
  
      /// Main method to override
  