anchor.diff:  %%      Riak's application environment.  It must be set to a string
   %%      representing the base directory where this backend should
   %%      store its files.
  --spec start(integer(), config()) -> {ok, state()} | {error, term()}.
  +-spec start(integer(), config()) -> {ok, state()}.
   start(Partition, Config) ->
       PartitionName = integer_to_list(Partition),
       ConfigRoot = app_helper:get_prop_or_env(fs2_backend_data_root, Config, riak_kv),
  
positive.code: -spec fold_keys(riak_kv_backend:fold_keys_fun(),
                  any(),
                  [{atom(), term()}],
                  state()) -> {ok, term()} | {async, fun()} | {error, term()}.
  fold_keys(FoldKeysFun, Acc, Opts, State) ->
      Bucket =  proplists:get_value(bucket, Opts),
      FoldFun = fold_keys_fun(FoldKeysFun, Bucket),
  
negative.code: -spec fold_objects(riak_kv_backend:fold_objects_fun(),
                     any(),
                     [{atom(), term()}],
                     state()) -> {ok, any()} | {async, fun()}.
  fold_objects(FoldObjectsFun, Acc, Opts, State) ->
      %% Warning: This ain't pretty. Hold your nose.
      Bucket =  proplists:get_value(bucket, Opts),
  