anchor.diff:  
   -ifdef(TEST).
   
  --dialyzer({no_match, trie_test_/0}).
   trie_test_() ->
       [{"basic representation",
         [?_assert(trie_new() =:= gb_trees:empty()),
  
positive.code: uniq([]) -> [].
  
  -ifdef(TEST).
  -dialyzer({[no_match, no_fail_call, no_improper_lists], uniq_test_/0}).
  uniq_test_() ->
      {"uniq",
       [?_assertError(function_clause, uniq(ok)),
  
negative.code:     io_lib:fwrite("*** ~ts ***\n~ts\n\n", [Title, Msg]).
  
  -ifdef(TEST).
  format_exception_test_() ->
      [?_assertMatch(
          "\nymmud:rorre"++_,
  