anchor.diff:  % Helper functions
   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   
  -% not ready yet:
  -%% -spec fill_ring_feeder(random, 1..1000, [db_parameter()])
  -%%         -> {db_type(), pos_integer(), [db_parameter()]}.
  -%% fill_ring_feeder(Type, DBSize0, Params) ->
  -%%     Params1 =
  -%%         case proplists:get_value(distribution, Params, uniform) of
  -%%             {non_uniform, RanGen} = EDist0 ->
  -%%                 DBSize = erlang:min(DBSize0, random_bias:numbers_left(RanGen)),
  -%%                 [{distribution, feeder_fix_rangen(EDist0, DBSize)} |
  -%%                      proplists:delete(fdistribution, Params)];
  -%%             _ ->
  -%%                 DBSize = DBSize0,
  -%%                 Params
  -%%         end,
  -%%     {Type, DBSize, Params1}.
  +-spec fill_ring_feeder(random, {1..1000, 1..1000}, [db_parameter()])
  +        -> {db_type(), pos_integer(), [db_parameter()]}.
  +fill_ring_feeder(Type, {Size0, Size1}, Params) ->
  +    % failures must be less than DB size!
  +    if Size0 >= Size1 -> DBSize = Size0, FSize = Size1;
  +       true           -> DBSize = Size1, FSize = Size0
  +    end,
  +    Params1 =
  +        case proplists:get_value(distribution, Params, uniform) of
  +            {non_uniform, _DBRanGen} = DBDist0 ->
  +                [{distribution, feeder_fix_rangen(DBDist0, DBSize)} |
  +                     proplists:delete(distribution, Params)];
  +            _ -> Params
  +        end,
  +    % set the given number of failures into the random number generator
  +    Params2 =
  +        case proplists:get_value(fdistribution, Params1, uniform) of
  +            {non_uniform, _FRanGen} = EDist0 ->
  +                [{fdistribution, feeder_fix_rangen(EDist0, FSize)} |
  +                     proplists:delete(fdistribution, Params1)];
  +            _ -> Params1
  +        end,
  +    {Type, DBSize, Params2}.
   
   % @doc  DBSize=Number of Data Entities in DB (without replicas)
   -spec fill_ring(db_type(), pos_integer(), [db_parameter()]) -> db_status().
  
positive.code: 
  % for tester:
  -export([get_db_feeder/3, get_db_feeder/4]).
  %% -export([fill_ring_feeder/3]).
  -export([feeder_fix_rangen/2]).
  
  -define(ReplicationFactor, 4).
  
negative.code:         wiki -> fill_wiki(Params, "barwiki-latest-pages-meta-current.db")
      end.
  
  -spec fill_random_feeder({1..1000, 1..1000}, [db_parameter()])
          -> {pos_integer(), [db_parameter()]}.
  fill_random_feeder(Sizes0, Params0) ->
      {random, DBSize, Params} = fill_ring_feeder(random, Sizes0, Params0),
      {DBSize, Params}.
  
  -spec fill_random(DBSize::pos_integer(), [db_parameter()]) -> db_status().
  fill_random(DBSize, Params) ->    
  