anchor.diff:      ]
     ).
   
  +start_helper_() -> 
  +  {ok, Pid} = start_link(), 
  +  Pid.
   stop_helper_(Pid) -> stop_helper_(Pid, 3000).
   stop_helper_(Pid, Timeout) ->
     true = exit(Pid, normal),
  
positive.code: 
  start_link_test_() -> 
    test_start_stop_(
      fun() -> {ok,Pid} = start_link(), Pid end,
      fun stop_helper_/1,
      "start_link test" 
    ).
  
negative.code:   { setup,
      fun()  -> 
        check_cwd_helper_(),
        { ok, Pid } = start_link("./dummyrrdtool -"),
        Pid
      end,
      fun stop_helper_/1,
  