anchor.diff:      _ = lists:foldl(fun(_, Old) -> rrd:add_now(1, Old) end, Init, lists:seq(1, 10000)),
       ok.
   
  -
  -%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  -%
  -% intervals:empty/0, intervals:is_empty/1, intervals:in/2 and intervals:is_continuous/1
  -%
  -%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  +%% @doc Converts a time (either a tuple as returned by erlang:now/0 or a number
  +%%      representing the number of microseconds since epoch) to the number of
  +%%      microseconds since epoch.
  +-spec time2us(util:time() | rrd:internal_time()) -> rrd:internal_time().
  +time2us({_, _, _} = Time) ->
  +    rrd:timestamp2us(Time);
  +time2us(Time) ->
  +    Time.
  +
   -spec prop_empty_rrd(SlotLength::rrd:timespan(), Count::1..10, Type::rrd:timeseries_type(),
                        StartTime::util:time() | rrd:internal_time(),
                        Offsets::[non_neg_integer(),...],
                        Times::[util:time() | rrd:internal_time(),...]) -> boolean().
   prop_empty_rrd(SlotLength, Count, Type, StartTime, Offsets, Times) ->
  -    R=rrd:create(SlotLength, Count, Type, StartTime),
  -    StartTime_us = case StartTime of
  -                       {_, _, _} -> rrd:timestamp2us(StartTime);
  -                       X         -> X
  -                   end,
  +    R = rrd:create(SlotLength, Count, Type, StartTime),
  +    StartTime_us = time2us(StartTime),
       ?equals(rrd:get_slot_start(0, R), StartTime_us),
       ?equals(rrd:get_type(R), Type),
       ?equals(rrd:get_slot_length(R), SlotLength),
  
positive.code:     _ = [?equals(rrd:get_value_by_offset(R, Offset), undefined) || Offset <- Offsets],
      true.
  
  tester_empty_rrd(_Config) ->
      tester:test(?MODULE, prop_empty_rrd, 6, 1000, [{threads, 2}]).
  
negative.code:             timestamp,
              add_nonexisting_timeslots,
              reduce_timeslots,
              tester_empty_rrd,
              tester_counter_rrd,
              tester_gauge_rrd
             ].
  suite() -> [ {timetrap, {seconds, 40}} ].
  
  