anchor.diff:  sub_tuple_to_list(_Tuple, _Pos, _Size) -> [].
   
   position(List, Pred) ->
  -  position(List, Pred, 1).
  +  position(List, Pred, 0).
   
   position([], _Pred, _Pos) ->
     0;
  
positive.code: dobserve_impl(Registry, Name, LabelValues, Value) ->
    case ets:lookup(?TABLE, key(Registry, Name, LabelValues)) of
      [Metric] ->
        {BucketPosition, SumPosition} =
          calculate_histogram_update_positions(Metric, Value),
        ets:update_element(?TABLE, key(Registry, Name, LabelValues),
                           {SumPosition, sum(Metric) + Value}),
        ets:update_counter(?TABLE, key(Registry, Name, LabelValues),
                           {BucketPosition, 1});
      [] ->
        insert_metric(Registry, Name, LabelValues, Value, fun dobserve_impl/4)
    end.
  
negative.code: %%====================================================================
  
  -define(TABLE, ?PROMETHEUS_HISTOGRAM_TABLE).
  -define(BOUNDS_POS, 2).
  -define(SUM_POS, 3).
  -define(BUCKETS_START, 4).
  -define(WIDTH, 16).
  
  %%====================================================================
  