anchor.diff:      {ok, 200, #{<<"block_hash">> := BlockHash}} = get_tx(ContractCallTxHash),
       {ok, 200, BlockHeader} = get_micro_block_header(BlockHash),
   
  -    {Value, BlockHeader}.
  +    {Value, #{header => BlockHeader, return => CallReturn}}.
   
   %% error_call_compute_func(NodeName, Pubkey, Privkey, EncodedContractPubkey,
   %%                         Function, Arguments)
  
positive.code: 
      %% Coinbase.
      ct:pal("Calling coinbase\n"),
      {CoinBaseValue,CBHeader} = call_compute_func(NodeName, CPubkey, CPrivkey,
                                                   EncodedContractPubkey,
                                                   <<"coinbase">>, <<"()">>),
      #{<<"value">> := CoinBase} = decode_data(<<"address">>, CoinBaseValue),
      ct:pal("CoinBase ~p\n", [CoinBase]),
      #{<<"prev_key_hash">> := CBKeyHash} = CBHeader,
  
negative.code: 
      %% Block timestamp.
      ct:pal("Calling timestamp\n"),
      {TimeStampValue, #{header := TSHeader}} =
          call_compute_func(NodeName, CPubkey, CPrivkey,
                            EncodedContractPubkey,
                            <<"timestamp">>, <<"()">>),
      #{<<"value">> := TimeStamp} = decode_data(<<"int">>, TimeStampValue),
      ct:pal("Timestamp ~p\n", [TimeStamp]),
      ?assertEqual(maps:get(<<"time">>, TSHeader), TimeStamp),
  
      %% Block height.
      ct:pal("Calling block_height\n"),
      {HeightValue,#{header := HeightHeader}} =
          call_compute_func(NodeName, DPubkey, DPrivkey,
                            EncodedContractPubkey,
                            <<"block_height">>, <<"()">>),
      #{<<"value">> := BlockHeight} = decode_data(<<"int">>, HeightValue),
      ct:pal("Block height ~p\n", [BlockHeight]),
      ?assertEqual(maps:get(<<"height">>, HeightHeader), BlockHeight),
  
      %% Difficulty.
      ct:pal("Calling difficulty\n"),
      {DiffValue,#{header := DiffHeader}} =
          call_compute_func(NodeName, DPubkey, DPrivkey,
                            EncodedContractPubkey,
                            <<"difficulty">>, <<"()">>),
      #{<<"value">> := Difficulty} = decode_data(<<"int">>, DiffValue),
      ct:pal("Difficulty ~p\n", [Difficulty]),
      #{<<"prev_key_hash">> := DiffKeyHash} = DiffHeader,
  