anchor.diff:  code_change(_, State, _) ->
       {ok, State}.
   
  +
   -spec sorted_piecelist(pieceset(), array()) -> [pos_integer()].
   sorted_piecelist(Pieceset, Numpeers) ->
       Piecelist = etorrent_pieceset:to_list(Pieceset),
       lists:sort(fun(A, B) ->
           array:get(A, Numpeers) =< array:get(B, Numpeers)
       end, Piecelist).
  +
   
   -spec decrement(pieceset(), array()) -> array().
   decrement(Pieceset, Numpeers) ->
  
positive.code:     NewState = State#state{
          subscriptions=NewSubscriptions},
      {reply, {ok, Ref, Piecelist}, NewState}.
  
  %% @private
  handle_cast(_, State) ->
  
negative.code:         IsMatching(SubPieceset)],
      [send_update(Sub, Numpeers) || Sub <- Matching],
      ok.
  
  
  -spec send_update(#subscription{}, array()) -> ok.
  send_update(Subscription, Numpeers) ->
  