anchor.diff:      [
        {history, {call,?MODULE,start_vnode,[index()]}},
        {history, {call,mock_vnode,get_index,[active_preflist1(S)]}},
  -     {history, {call,mock_vnode,get_counter,[active_preflist1(S)]}}
  +     {history, {call,mock_vnode,get_counter,[active_preflist1(S)]}},
  +     {history, {call,mock_vnode,neverreply,[active_preflist(S)]}}
        %% {history, {call,?MODULE,noop,[2]}},
        %%{history, {call,?MODULE,noop,[3]}}].
       ].
   
   precondition(_From,_To,#qcst{started=Started},{call,?MODULE,start_vnode,[Index]}) ->
       not lists:member(Index, Started);
  +precondition(_From,_To,#qcst{started=Started},{call,mock_vnode,get_index,[Preflist]}) ->
  +    preflist_is_active(Preflist, Started);
  +precondition(_From,_To,#qcst{started=Started},{call,mock_vnode,get_counter,[Preflist]}) ->
  +    preflist_is_active(Preflist, Started);
  +precondition(_From,_To,#qcst{started=Started},{call,mock_vnode,neverreply,[Preflist]}) ->
  +    preflist_is_active(Preflist, Started);
   precondition(_From,_To,_S,_C) ->
       true.
   
  
positive.code: active_index(#qcst{started=Started}) ->
      elements(Started).
  
  active_preflist1(S) ->
      {active_index(S), node()}.
  
  initial_state() ->
      stopped.
  
negative.code:     exit(Pid, kill),
      ok = wait_for_pid(Pid).
  
  preflist_is_active({Index,_Node}, Started) ->
      lists:member(Index, Started);
  preflist_is_active(Preflist, Started) ->
      lists:all(fun({Index,_Node}) -> lists:member(Index, Started) end, Preflist).
  
  
  wait_for_pid(Pid) ->
      Mref = erlang:monitor(process, Pid),
      receive
  