anchor.diff:  %%      Input:  Partition: The partition identifier to check
   %%              Preflist: A list of pairs {Partition, Node}
   %%      Return: true | false
  +%%
   -spec preflist_member(partition(), preflist()) -> boolean().
   preflist_member(Partition,Preflist) ->
       lists:any(fun({P, _}) -> P =:= Partition end, Preflist).
  
positive.code: %%              Payload of the operation
  %%              OpId: Unique operation id
  %%      Output: {ok, {vnode_id, op_id}} | {error, Reason}
  handle_command({append, LogId, OpId, Payload}, _Sender,
                 #state{logs_map=Map, partition=Partition}=State) ->
      case get_log_from_map(Map, LogId) of
  
negative.code: %%                      F: Function to apply when floding the log (dets)
  %%                      Acc: Folded data
  %%      Return: Folded data of all the logs.
  %%
  -spec join_logs([{preflist(), log()}], fun(), term()) -> term().
  join_logs([], _F, Acc) ->
      Acc;
  