anchor.diff:  
   -spec request_histogram(Size::pos_integer(), SourceId::comm:mypid()) -> ok.
   request_histogram(Size, SourcePid) when Size < 1 ->
  -    error(badarg, [Size, SourcePid]);
  +    erlang:error(badarg, [Size, SourcePid]);
   
   request_histogram(Size, SourcePid) ->
       gossip:start_gossip_task(?MODULE, [Size, SourcePid]).
  
positive.code: 
  
  -spec finish_request(State) -> {ok, State} when
      State :: state().
  finish_request(State) ->
      Histo = load_data_get(histo, state_get(load_data, State)),
      case state_get(leader, State) of
  
negative.code:     case ets:lookup(State, Key) of
          [] ->
              log:log(error, "[ ~w ] Lookup of ~w in ~w failed~n", [state_get(instance, State), Key, State]),
              erlang:error(lookup_failed, [Key, State]);
          [{Key, Value}] -> Value
      end.
  
  