anchor.diff:  -spec update_helper_args(storage:id(), helper:name(), helper:args()) ->
       ok | {error, term()}.
   update_helper_args(StorageId, HelperName, Changes) when is_map(Changes) ->
  -    Updater = fun(Helper) -> helper:update_args(Helper, Changes) end,
  -    case update_helper(StorageId, HelperName, Updater) of
  +    UpdateFun = fun(Helper) -> helper:update_args(Helper, Changes) end,
  +    case update_helper(StorageId, HelperName, UpdateFun) of
           ok -> rtransfer_put_storage(StorageId);
           Error -> Error
       end.
  
positive.code:     end.
  
  
  %%--------------------------------------------------------------------
  %% @doc
  %% Replaces storage with a new one of the same name.
  %% @end
  %%--------------------------------------------------------------------
  -spec replace_helper(record(), helper:name(), NewHelper :: helpers:helper()) ->
      record().
  replace_helper(#storage{helpers = OldHelpers} = Storage, HelperName, NewHelper) ->
      NewHelpers = lists:keyreplace(HelperName, #helper.name, OldHelpers, NewHelper),
      Storage#storage{helpers = NewHelpers}.
  
  
  -spec update_name(StorageId :: id(), NewName :: name()) -> ok.
  update_name(StorageId, NewName) ->
      Result = update(StorageId, fun(#storage{} = Storage) ->
          {ok, Storage#storage{name = NewName}}
      end),
      case Result of
          {ok, _} -> rtransfer_put_storage(StorageId);
          Error -> Error
      end.
  
negative.code: %%--------------------------------------------------------------------
  %% @private
  %% @doc
  %% Replaces storage with given name.
  %% @end
  %%--------------------------------------------------------------------
  -spec replace_helper(record(), helper:name(), NewHelper :: helpers:helper()) ->
      record().
  replace_helper(#storage{helpers = OldHelpers} = Storage, HelperName, NewHelper) ->
      NewHelpers = lists:keyreplace(HelperName, #helper.name, OldHelpers, NewHelper),
      Storage#storage{helpers = NewHelpers}.
  
  
  %%--------------------------------------------------------------------
  %% @private
  %% @doc
  %% Adds or updates storage in rtransfer config.
  %% @end
  %%--------------------------------------------------------------------
  