anchor.diff:  get_zones(Who) ->
   	Cookie = cookie(Who),
   	ibrowse:send_req(?zone_url, [Cookie, ?accepts, ?contenttype], get, []).
  +
  +get_auras(Who) ->
  +	Cookie = cookie(Who),
  +	ibrowse:send_req(?aura_url, [Cookie, ?accepts, ?contenttype], get, []).
   
   delete_zone(Nth, State) ->
   	#state{zones = Zones} = State,
  
positive.code: 	end || {Z, T} <- Pairs],
  	true;
  
  postcondition(State, {call, _, delete_zone, _}, {ok, "204", _, _}) ->
  	true;
  
  
negative.code: %% preconditions
  %% =======================================================
  
  precondition(S, {call, _, Call, _}) ->
  	Needs = [
  		{zones, [delete_zone]},
  		{auras, [delete_aura]}
  	],
  	IsNeeds = [N || {N, List} <- Needs, lists:member(Call, List)],
  	case IsNeeds of
  		[] -> true;
  		[zones] ->
  			length(S#state.zones) > 0;
  		[auras] ->
  			length(S#state.auras) > 0
  	end.
  
  %% =======================================================
  %% next_state
  