anchor.diff:  
   prop_decode_legacy_big() ->
       ?FORALL(T, big(),
  +	    sext:decode(sext:encode(T, true)) == T).
  +
  +prop_decode_legacy_neg_big() ->
  +    ?FORALL(T, neg_big(),
   	    sext:decode(sext:encode(T, true)) == T).
   
   prop_encode_sb32() ->
  
positive.code:      [
        fun() -> t(run(N, prop_encode, fun prop_encode/0)) end
        , fun() -> t(run(N, prop_decode_legacy_big, fun prop_decode_legacy_big/0)) end
        , fun() -> t(run(N, prop_prefix_equiv,fun prop_prefix_equiv/0))end
        , fun() -> t(run(N, prop_sort, fun prop_sort/0)) end
        , fun() -> t(run(N, prop_encode_sb32, fun prop_encode_sb32/0)) end
        , fun() -> t(run(N, prop_sort_sb32, fun prop_sort_sb32/0)) end
        , fun() -> t(run(N, prop_partial_decode1, fun prop_partial_decode1/0)) end
  
negative.code:                         comp(X1,X2) == comp_i(T1,T2))
              end).
  
  prop_sort_neg_big() ->
      ?FORALL({T1,T2}, {neg_big(), neg_big()},
              begin
                  {X1,X2} = {sext:encode(T1), sext:encode(T2)},
                  collect(size(term_to_binary({T1,T2})),
                          comp(X1,X2) == comp_i(T1,T2))
              end).
  
  prop_sort_sb32() ->
      ?FORALL({T1,T2}, {term_(), term_()},
              begin
  