anchor.diff:          {empty, _} ->
               error(badarg);
           {{value, Head}, Tail} ->
  -            {Head, Tail}
  +            NewReqs = Requestqueue#requestqueue{queue=Tail},
  +            {Head, NewReqs}
       end.
   
   
  
positive.code:      ?_assertEqual(0, ?rqueue:needs(Q3)),
       ?_assertEqual(0, ?rqueue:needs(Q4))].
  
  
  -endif.
  
  
negative.code: 
  %% @doc
  %% @end
  -spec push([requestspec()], #requestqueue{}) -> requestqueue().
  push(Requests, Requestqueue) ->
      #requestqueue{queue=Queue} = Requestqueue,
      TmpQueue = queue:from_list(Requests),
      NewQueue = queue:join(Queue, TmpQueue),
      Requestqueue#requestqueue{queue=NewQueue}.
  
  
  %% @doc
  %% @end
  -spec pop(#requestqueue{}) -> {requestspec(), requestqueue()}.
  pop(Requestqueue) ->
      #requestqueue{queue=Queue} = Requestqueue,
  