anchor.diff:                    [#redundant_node{node = Node}|_], Redundancies) when Node == erlang:node() ->
       %% Retrieve an head of object,
       %%     then compare it with requested 'Etag'
  -    Ret = case leo_object_storage_api:head({AddrId, Key}) of
  -              {ok, MetaBin} ->
  -                  Metadata = binary_to_term(MetaBin),
  -                  case Metadata#?METADATA.checksum of
  -                      ETag ->
  -                          {ok, match};
  -                      _ ->
  -                          []
  -                  end;
  -              _ ->
  -                  []
  -          end,
  +    HeadRet =
  +        case leo_object_storage_api:head({AddrId, Key}) of
  +            {ok, MetaBin} ->
  +                Metadata = binary_to_term(MetaBin),
  +                case Metadata#?METADATA.checksum of
  +                    ETag ->
  +                        {ok, match};
  +                    _ ->
  +                        []
  +                end;
  +            _ ->
  +                []
  +        end,
   
       %% If the result is 'match', then response it,
       %% not the case, retrieve an object by key
  -    case Ret of
  +    case HeadRet of
           {ok, match} = Reply ->
               Reply;
           _ ->
  
positive.code:     end;
  
  read_and_repair_1(ReadParameter,
                    [#redundant_node{node = Node}|_],_Redundancies) ->
      RPCKey = rpc:async_call(Node, ?MODULE, get, [ReadParameter, []]),
      Reply  = case rpc:nb_yield(RPCKey, ?DEF_REQ_TIMEOUT) of
                   {value, {ok, Meta, Bin}} ->
                       {ok, Meta, #?OBJECT{data = Bin}};
                   {value, {ok, match} = Ret} ->
  
negative.code:                  timeout = Cause ->
                       {error, Cause}
               end,
      read_and_repair_2(RetRPC, ReadParameter, []).
  
  %% @private
  read_and_repair_2({ok, Metadata, #?OBJECT{data = Bin}}, #read_parameter{}, []) ->
      {ok, Metadata, Bin};
  read_and_repair_2({ok, match} = Reply, #read_parameter{},_Redundancies) ->
      Reply;
  read_and_repair_2({ok, Metadata, #?OBJECT{data = Bin}},
                    #read_parameter{quorum = Quorum} = ReadParameter, Redundancies) ->
  