anchor.diff:      check_format(Version0Subs, NewSubs);
   check_format([], NewStyleSubs) -> NewStyleSubs.
   
  -%% returns only the Subscriptions of Subs1 that are not also Subscriptions of Subs2
  +%% returns only the Subscriptions of Subs1 that are not also
  +%% Subscriptions of Subs2. Assumes the subs are sorted by nodenames.
   subtract(Subs1, Subs2) ->
       subtract(Subs1, Subs2, []).
   
  
positive.code:        []
        }, get_changes(Old, New)).
  
  change_node_test_() ->
      Subs = [{node_a, false, [{a,1},{b,1}]},
              {node_b, false, [{c,2}]}],
  
negative.code:         NewNSubs ->
              subtract(Subs1, Subs2, [{N, NewNSubs}|Acc])
      end;
  subtract([{N1, _, _}|_] = Subs1, [{N2,_,_}|T2], Acc) when N1 > N2->
      subtract(Subs1, T2, Acc);
  subtract([{N, _, NSubs1}|Subs1], Subs2, Acc) ->
      subtract(Subs1, Subs2, [{N, NSubs1}|Acc]);
  subtract([], _, Acc) -> lists:reverse(Acc).
  
  
  get_nodes(Subs) ->
      lists:foldl(fun({N, _, _}, Acc) -> [N|Acc] end, [], Subs).
  