anchor.diff:  
   %% @doc Atomically perform a set_change operation and a commit (not as part of a transaction).
   -spec number_add(client_key(), ToAdd::number())
  -           -> numberop_result().
  +           -> numberop_result() | {fail, abort}.
   number_add(Key, ToAdd) ->
       ReqList = [{number_add, Key, ToAdd}, {commit}],
       {_TLog, [Res1, Res2]} = req_list(tx_tlog:empty(), ReqList),
  
positive.code: %%      If the value stored at Key is the same as OldValue, then NewValue will
  %%      be stored.
  -spec test_and_set(Key::client_key(), OldValue::client_value(), NewValue::client_value())
          -> testandset_result().
  test_and_set(Key, OldValue, NewValue) ->
      ReqList = [{test_and_set, Key, OldValue, NewValue}, {commit}],
      {_TLog, [Res1, Res2]} = req_list(tx_tlog:empty(), ReqList),
  
negative.code: 
  %% @doc Atomically perform a set_change operation and a commit (not as part of a transaction).
  -spec set_change(client_key(), ToAdd::[client_value()], ToRemove::[client_value()])
             -> listop_result() | {fail, abort}.
  set_change(Key, ToAdd, ToRemove) ->
      ReqList = [{set_change, Key, ToAdd, ToRemove}, {commit}],
      {_TLog, [Res1, Res2]} = req_list(tx_tlog:empty(), ReqList),
  