anchor.diff:      {ok, Objects} = eredis:q(Eredis, ["KEYS", prefix(Prefix, "*")]),
       Result = lists:foldl(
           fun(Id, Acc) ->
  -            {ok, Value1} = do_get(Eredis, Prefix, Id),
  -            Value = decode(Value1),
  -            {NewValue, InnerResult} = Function({Id, decode(Value)}),
  +            {ok, Value} = do_get(Eredis, Prefix, Id),
  +            {NewValue, InnerResult} = Function({Id, Value}),
               case do_put(Eredis, Prefix, Id, NewValue) of
                   ok ->
                       Acc ++ [InnerResult]
  
positive.code:     {ok, Objects} = eredis:q(Eredis, ["KEYS", prefix(Prefix, "*")]),
      Acc1 = lists:foldl(
          fun(Id, Acc) ->
              {ok, Value1} = do_get(Eredis, Prefix, Id),
              Value = decode(Value1),
              Function({Id, decode(Value)}, Acc)
          end,
          Acc0,
          Objects
  
negative.code: handle_call({update, Id, Function}, _From, #state{eredis=Eredis, prefix=Prefix}=State) ->
      Result = case do_get(Eredis, Prefix, Id) of
          {ok, Value} ->
              {NewValue, InnerResult} = Function({Id, Value}),
              case do_put(Eredis, Prefix, Id, NewValue) of
                  ok ->
                      InnerResult
  