anchor.diff:          _ ->
               lists:keyreplace(K, 1, Existing, New)
       end;
  +%% TODO: deprecate 'environment' tuples, as they're not longer used
   extend({environment, _}=New, Existing) ->
       [New|Existing];
   extend({environment, _, _}=New, Existing) ->
  
positive.code: merge(New, Existing) ->
      append_if_missing(fun lists:member/2, New, Existing).
  
  extend({Path, Spec}=New, Existing) when Path =:= dir orelse
                                          Path =:= file ->
      %% TODO: this isn't very flexible - make it simpler to use...
  
negative.code:             Value
      end.
  
  get_env() ->
      gen_server:call(?MODULE, list).
  
  