anchor.diff:  -define(ru, rubis_utils).
   -define(default_group, <<"global_index">>).
   
  +-define(committed, {ok, []}).
  +
   -type key() :: term().
   -type reason() :: atom().
   
  
positive.code:     ok = pvc:update_keys({ItemKey, ItemObj}, TxId),
      ok = pvc_indices:index(CategoryIndex, CategoryId, ItemKey, TxId),
      ok = pvc_indices:index(SellerIndex, SellerId, ItemKey, TxId),
      {ok, []} = pvc:commit_transaction(TxId),
  
      {ok, ItemKey}.
  
  about_me(UserId) ->
      UserGroup = rubis_utils:get_grouping(UserId),
      SellerIndex = ?ru:gen_index_name(UserGroup, items_seller_id),
      BidderIndex = ?ru:gen_index_name(UserGroup, bids_bidder_id),
      CommentIndex = rubis_utils:gen_index_name(UserGroup, comments_to_id),
      BuyerIndex = rubis_utils:gen_index_name(UserGroup, buy_now_buyer_id),
  
      {ok, TxId} = pvc:start_transaction(),
      {ok, [#user{username = Username}]} = pvc:read_keys(UserId, TxId),
  
negative.code:     {ok, [<<>>]} = pvc:read_keys(RegionKey, TxId),
      ok = pvc:update_keys({RegionKey, RegionName}, TxId),
      ok = pvc_indices:index(NameIndex, RegionName, RegionKey, TxId),
      Commit = pvc:commit_transaction(TxId),
  
      case Commit of
          ?committed ->
              {ok, RegionKey};
          {error, Reason} ->
              {error, Reason}
      end.
  
  -spec put_category(binary()) -> {ok, key()} | {error, reason()}.
  put_category(CategoryName) ->
      %% Each category has its own grouping, determined by their region name (unique)
      ChosenPartition = log_utilities:get_key_partition(CategoryName),
  