anchor.diff:  
   prop_limit_ok() ->
       ?FORALL(
  -       MaxSize, c_size(),
  -       ?FORALL(Cache, cache(MaxSize),
  +       {MaxSize, Opts}, {c_size(), opts()},
  +       ?FORALL(Cache, cache(MaxSize, Opts),
                  begin
                      %% io:format("~p~n", [Cache]),
                      {H, _, _} = eval(Cache),
  
positive.code: 
  prop_map_comp() ->
      ?FORALL(
         MaxSize, c_size(),
         ?FORALL(Cache, cache(MaxSize),
                 begin
                     {H, T, Ds} = eval(Cache),
                     TreeKs = all_keys_t(T),
  
negative.code: v_time() ->
      nat().
  
  pnat() ->
      ?SUCHTHAT(N, nat(), N > 0).
  
  opts() ->
      [
       {buckets, pnat()},
       {age_cycle, pnat()},
       {initial_data_size, pnat()},
       {initial_entries, pnat()},
       {hash_seed, pnat()}
      ].
  
  cache(MaxSize, Opts, 0) ->
      {call, ?MODULE, new, [MaxSize, Opts]};
  
  cache(MaxSize, Opts, Size) ->
      ?LAZY(
         ?LETSHRINK(
            [H], [cache(MaxSize, Opts, Size -1)],
            frequency(
              [
               {1,   {call, ?MODULE, age, [H]}},
  