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