anchor.diff:      ?assertMatch({Question, _} when is_binary(Question), call_contract(OperatorAcc, OCt, getQuestion, string, {OCt, QueryId}, S)),
       Response = maps:get(response, Opts, 4001),
       ?assertMatch(_ when is_integer(Response), Response),
  -    {{}, S1} = call_contract(OperatorAcc, OCt, respond, {tuple, []}, {OCt, QueryId, 0, Response}, TxOpts, S),
  +    {R, S1} = call_contract(OperatorAcc, OCt, respond, {tuple, []}, {OCt, QueryId, 0, Response}, TxOpts, S),
       ?assertMatch({{some, Response}, _}, call_contract(OperatorAcc, OCt, getAnswer, {option, word}, {OCt, QueryId}, S1)),
  -    {ok, S1}.
  +    {R, S1}.
   
   oracle_check_and_respond_from_remote_contract(OperatorAcc, RCt, OCt, QueryId, Opts, TxOpts, S) ->
       ?assertMatch({Question, _} when is_binary(Question), call_contract(OperatorAcc, OCt, getQuestion, string, {OCt, QueryId}, S)),
       Response = maps:get(response, Opts, 4001),
  -    {{}, S1} = call_contract(OperatorAcc, RCt, callRespond, {tuple, []}, {OCt, OCt, QueryId, 0, Response}, TxOpts, S),
  +    {R, S1} = call_contract(OperatorAcc, RCt, callRespond, {tuple, []}, {OCt, OCt, QueryId, 0, Response}, TxOpts, S),
       ?assertMatch({{some, Response}, _}, call_contract(OperatorAcc, OCt, getAnswer, {option, word}, {OCt, QueryId}, S1)),
  -    {ok, S1}.
  +    {R, S1}.
   
   -record(oracle_cbs, {init, register, query, respond}).
   %%
  
positive.code: sophia_oracles_qfee__init_and_register_and_query_(Init, RegisterOracle, CreateQuery) ->
      {OracleAcc, CallingCt} = call(Init, []),
      S0 = state(),
      ok = call(RegisterOracle, [CallingCt, OracleAcc]),
      S1 = state(),
      R = call(CreateQuery, [CallingCt, OracleAcc]),
      {R,
  
negative.code:       S1] %% State after oracle registration.
      } = sophia_oracles_qfee__init_and_register_and_query_(Init, RegisterOracle, CreateQuery),
      S2 = state(),
      {} = call(RespondQuery, [CallingCt, OracleAcc, QId]),
      {{OracleAcc, CallingCt},
       [S0, S1, S2]}.
  
  