anchor.diff:  
   %% @doc writes the value of a key
   %% @spec write(key(), value()) -> ok | {fail, term()}
  +-spec write(key(), value()) -> ok | {fail, term()}.
   write(Key, Value) ->
       case util:tc(transaction_api, single_write, [Key, Value]) of
           {_Time, commit} ->
  
positive.code: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  
  %% @type key() = term(). Key
  %% @type value() = term(). Value
  
  process_request_list(TLog, ReqList) ->
      erlang:put(instance_id, process_dictionary:find_group(cs_node)),
  
negative.code:     transaction_api:delete(Key, 2000).
  
  %% @doc atomic compare and swap
  %% @spec test_and_set(key(), value(), value()) -> ok | {fail, term()}
  -spec test_and_set(key(), value(), value()) -> ok | {fail, Reason::term()}.
  test_and_set(Key, OldValue, NewValue) ->
      TFun = fun(TransLog) ->
                     {Result, TransLog1} = transaction_api:read(Key, TransLog),
  