anchor.diff:    maybe_delete(Filename).
   
   t_01_test() ->
  -  Filename = "redbug.txt",
  +  Filename = "redbug01.txt",
     {_,_} = redbug:start("lists:sort",[{print_file,Filename},arity,debug]),
     [1,2,3] = lists:sort([3,2,1]),
     timer:sleep(100),
  
positive.code:   maybe_delete("foo0.trc").
  
  t_9_test() ->
    Filename = "redbug.txt",
    Options = [{print_file, Filename}, {time, 999}, {print_return, false}],
    {_,_} = redbug:start("lists:sort->return",[debug|Options]),
    [1,2,3] = lists:sort([3,2,1]),
  
negative.code:   maybe_delete(Filename).
  
  t_4_test() ->
    Filename = "redbug4.txt",
    Pid = spawn(fun()->receive P when is_pid(P)->P!ding;quit->ok end end),
    {_,_} = redbug:start('receive',[{procs,Pid},{print_file,Filename},debug]),
    Pid ! pling,
  