anchor.diff:  price([{"productOfferPriceAlteration", {struct, L} = Alteration} | T], Acc)
   		when is_list(L) ->
   	price(T, Acc#price{alteration = alteration(Alteration)});
  +price([{"plaRef", {struct, L} = PlaRef} | T], Acc)
  +		when is_list(L) ->
  +	price(T, Acc#price{pla = pla_ref(PlaRef)});
   price([], Acc) ->
   	Acc.
   
  
positive.code: 		false ->
  			case lists:keyfind(Key, 1, Query) of
  				{_, Value} ->
  					{exact, Value};	
  				false ->
  					'_' 
  			end
  	end.
  
  
negative.code: price([alteration | T], #price{alteration = Alteration} = P, Acc)
  		when is_record(Alteration, alteration) ->
  	price(T, P, [{"productOfferPriceAlteration", alteration(Alteration)} | Acc]);
  price([pla | T], #price{pla = PlaRef} = P, Acc) ->
  	price(T, P, [{"plaRef", pla_ref(PlaRef)} | Acc]);
  price([_ | T], P, Acc) ->
  	price(T, P, Acc);
  price([], _P, Acc) ->
  