anchor.diff:  
   %% What node-specific operations should be called.
   node_commands() ->
  -    [{call, ?MODULE, next_id, [node_name()]}].
  +    [
  +     {call, ?MODULE, next_id, [node_name()]},
  +     {call, ?MODULE, set_fault, [node_name(), boolean()]}
  +    ].
   
   %% Assertion commands.
   node_assertion_functions() ->
  
positive.code:     ?PROPERTY_MODULE:command_preamble(RunnerNode, [max_id]),
  
      Results = lists:map(fun(Node) ->
          {ok, Result} = rpc:call(?NAME(Node), paxoid, max_id, [?GROUP], 5000),
          node_debug("result of max_id: ~p~n", [Result]),
          {Node, Result}
      end, names()),
  
  
negative.code:     % end, Results);
  
      true;
  node_postcondition(_NodeState, {call, ?MODULE, set_fault, [_Node, _Value]}, ok) ->
      true;
  node_postcondition(_NodeState, {call, ?MODULE, sleep, []}, _Result) ->
      true;
  node_postcondition(_NodeState, {call, ?MODULE, next_id, [_Node]}, {badrpc,timeout}) ->
      false;
  node_postcondition(#node_state{counter=Counter}, {call, ?MODULE, next_id, [_Node]}, Value) ->
      node_debug("postcondition received ~p from next_id when value should be: ~p", [Value, Counter + 1]),
  
      case Counter + 1 =:= Value of 
          false ->
              node_debug("********* violation!~n", []),
              ok;
          true ->
              ok
      end,
  
      true;
  node_postcondition(_NodeState, Command, Response) ->
      node_debug("generic postcondition fired (this probably shouldn't be hit) for command: ~p with response: ~p", 
                 [Command, Response]),
  