anchor.diff:                            {error, term()}.
   active_manifests({ok, RiakObject, Manifests}) -> 
       {ok, RiakObject, riak_cs_manifest_utils:active_manifests(Manifests)};
  -active_manifests({error, _}=Error) -> Error.
  +active_manifests({error, _}=Error) -> 
  +    Error.
   
   -spec clean_manifests([lfs_manifest()], pid()) -> [lfs_manifest()].
   clean_manifests(ActiveManifests, RiakcPid) ->
  
positive.code:     {ok, [binary()]} | {error, term()}.
  gc_active_manifests(Bucket, Key, RiakcPid, UUIDs) ->
     case get_active_manifests(Bucket, Key, RiakcPid) of
          {ok, _RiakObject, []} -> {ok, UUIDs};
          {ok, RiakObject, Manifests} ->
              UnchangedManifests = clean_manifests(Manifests, RiakcPid),
              case gc_manifests(UnchangedManifests, RiakObject, Bucket, Key, RiakcPid) of
                  {error, _}=Error -> Error;
                  NewUUIDs -> gc_active_manifests(Bucket, Key, RiakcPid, UUIDs ++ NewUUIDs)
              end;
          {error, notfound} ->{ok, UUIDs};
          {error, _}=Error -> Error
      end.
  
  -spec get_active_manifests(binary(), binary(), pid()) ->
  
negative.code: check({ok, _}, Val) -> 
      Val;
  check({error, _}=Error, _Val) -> 
      Error.
  
  %% @private
  -spec gc_specific_manifests(UUIDsToMark :: [binary()],
  