anchor.diff:  
   
   %% @doc
  -%%
  +%% Decrement the number of peers providing a piece by one and
  +%% reprioritize the pieces in the scarcity list.
   %% @end
   -spec decrement(pos_integer(), #scarcity{}) -> scarcity().
   decrement(Index, Scarcity) ->
  
positive.code: 
  
  %% @doc
  %%
  %% @end
  -spec next(term()) -> pos_integer().
  next(Iterator) ->
      case gb_sets:next(Iterator) of
          none ->
  
negative.code: 
  
  %% @doc  
  %% Ensure that a piece is a member of the scarcity list.
  %% @end
  -spec assert_member(pos_integer(), array()) -> ok.
  assert_member(Index, Counters) ->
  