anchor.diff:    Filename  = "/tmp/queue1.bin",
     {ok, Mem} = open(Filename, 1024, [auto_unlink]),  %% Automatically delete file
     ?assert(filelib:is_regular(Filename)),
  +  ?assertEqual(nil, peek_front(Mem)),
  +  ?assertEqual(nil, peek_back(Mem)),
     % Enqueue data
  -  ?assertEqual([], [R || R <- [push(Mem, I) || I <- [a,b,c,1,2,3]], R /= ok]),
  +  ?assertEqual(ok,  push(Mem, a)),
  +  ?assertEqual(a,   peek_front(Mem)),
  +  ?assertEqual(a,   peek_back(Mem)),
  +
  +  ?assertEqual(ok,  push(Mem, b)),
  +  ?assertEqual(a,   peek_front(Mem)),
  +  ?assertEqual(b,   peek_back(Mem)),
  +
  +  ?assertEqual([], [R || R <- [push(Mem, I) || I <- [c,1,2,3]], R /= ok]),
   
     ?assertEqual([a,b,c,1,2,3], lists:reverse(peek(Mem, [], fun(I,S) -> {cont, [I | S]} end))),
   
  
positive.code: %% leave the queue unmodified. This function has a constant-time complexity. It returns
  %% the result of evaluating `Fun'.
  try_pop(Mem, Fun) when is_function(Fun, 1) ->
    case pop_internal(Mem, Fun) of
      {Res, _IsEnd} ->
        Res;
      nil ->
  
negative.code:   {reply, Msg, State};
  
  handle_call(peek, _From, #state{mem=Mem} = State) ->
    Msg = peek_front(Mem),
    {reply, Msg, State};
  
  handle_call({try_pop, Fun}, _From, #state{mem=Mem} = State) ->
  