anchor.diff:  size(<<>>, Acc) ->
       Acc.
   
  +%% @doc
  +%% Return the lowest piece index that is a member of this set.
  +%% If the piece set is empty, exit with reason badarg
  +%% @end
  +-spec min(pieceset()) -> pos_integer().
  +min(Pieceset) ->
  +    #pieceset{elements=Elements} = Pieceset,
  +    min_(Elements, 0).
  +
  +min_(<<>>, _) ->
  +    error(badarg);
  +min_(<<1:1, _/bitstring>>, Index) ->
  +    Index;
  +min_(<<0:1, Rest/bitstring>>, Index) ->
  +    min_(Rest, Index + 1).
  +
  +
   paddinglen(Size) ->
       Length = 8 - (Size rem 8),
       case Length of
  
positive.code:     Set1 = ?set:from_list(lists:seq(0,7), 8),
      ?assertEqual(Set0, Set1).
  
  %%
  %% Modifying the contents of a pieceset
  %%
  
negative.code:          insert/2,
           intersection/2,
           difference/2,
           size/1,
           min/1]).
  
  -record(pieceset, {
      size :: pos_integer(),
  