anchor.diff:  
   process_request('ReadOnlyTx', #{keys := Keys}) ->
       {ok, TxId} = pvc:start_transaction(),
  -    case pvc:read_keys(Keys, TxId) of
  +    case sequential_read(Keys, TxId) of
           {error, _}=ReadError ->
               ReadError;
  -        {ok, _} ->
  +        ok ->
               Commit = pvc:commit_transaction(TxId),
               case Commit of
                   ?committed ->
  
positive.code: 
  -export([process_request/2]).
  
  process_request('Ping', _) ->
      {ok, TxId} = pvc:start_transaction(),
      Commit = pvc:commit_transaction(TxId),
  
negative.code:     Updates = lists:map(fun(#{key := K, value := V}) -> {K, V} end, OpList),
  
      {ok, TxId} = pvc:start_transaction(),
      case sequential_read(Keys, TxId) of
          {error, _}=ReadError ->
              ReadError;
          ok ->
              ok = pvc:update_keys(Updates, TxId),
              Commit = pvc:commit_transaction(TxId),
              case Commit of
  