anchor.diff:  -spec mam_lookup_messages_iq(binary(), binary(), binary(), binary()) ->
       exml:element().
   mam_lookup_messages_iq(QueryId, Start, End, WithJID) ->
  +    mam_lookup_messages_iq(QueryId, Start, End, WithJID, false).
  +
  +-spec mam_lookup_messages_iq(binary(), binary(), binary(), binary(), term()) ->
  +    exml:element().
  +mam_lookup_messages_iq(QueryId, Start, End, WithJID, Simple)
  +  when Simple =:= true; Simple =:= false ->
       Fields = [field_el(<<"FORM_TYPE">>, <<"hidden">>, ?NS_MAM),
                 field_el(<<"start">>, <<"text-single">>, Start),
                 field_el(<<"end">>, <<"text-single">>, End),
                 field_el(<<"with">>, <<"jid-single">>, WithJID)
                ],
  -    mam_archive_query(QueryId, [Fields]).
  -
  +    WithSimpleField =
  +        case Simple of
  +            true -> [field_el(<<"simple">>, <<"boolean">>, <<"true">>) | Fields];
  +            false -> Fields
  +        end,
  +    mam_archive_query(QueryId, WithSimpleField);
   %% Include an rsm id for a particular message.
  --spec mam_lookup_messages_iq(binary(), binary(), binary(), binary(), term()) ->
  +mam_lookup_messages_iq(QueryId, Start, End, WithJID, DirectionWMessageId) ->
  +    mam_lookup_messages_iq(QueryId, Start, End, WithJID, DirectionWMessageId, false).
  +
  +-spec mam_lookup_messages_iq(binary(), binary(), binary(), binary(), term(), boolean()) ->
       exml:element().
  -mam_lookup_messages_iq(QueryId, Start, End, WithJID, DirectionWMessageId) ->
  +mam_lookup_messages_iq(QueryId, Start, End, WithJID, DirectionWMessageId, Simple) ->
       IQ = #xmlel{children=[Q]} = mam_lookup_messages_iq(QueryId, Start, End,
  -                                                       WithJID),
  +                                                       WithJID, Simple),
       RSM  = defined([fmapM(fun rsm_after_or_before/1, DirectionWMessageId)]),
       Other = Q#xmlel.children,
       Q2 = Q#xmlel{children = Other ++ RSM},
  
positive.code: %% XEP-0313: Message Archive Management
  -export([mam_archive_query/1,
           mam_lookup_messages_iq/4,
           mam_lookup_messages_iq/5
          ]).
  
  %% XEP-0333: Chat Markers
  
negative.code:                       %% no need to create form element
                        []
                end,
  
      escalus_stanza:iq(
        <<"set">>,
        [#xmlel{
  