anchor.diff:  -endif.
   
   -export([new/1,
  +         empty/1,
  +         full/1,
            from_binary/2,
            to_binary/1,
            from_list/2,
  
positive.code: -spec is_full(pieceset()) -> boolean().
  is_full(Pieceset) ->
      #pieceset{elements=Elements} = Pieceset,
      is_binary(Elements) orelse error(badarg),
      is_full_(Elements).
  
  is_full_(<<Pieces:16, Rest/bitstring>>) ->
  
negative.code: 
  prop_not_full() ->
      ?FORALL({Elem, Size},
      ?SUCHTHAT({E, S}, {non_neg_integer(), pos_integer()}, E < S),
      begin
          All = lists:seq(0, Size - 1),
          Not = lists:delete(Elem, All),
  