anchor.diff:  
   
   rand_tuple() ->
  -    case random:uniform(3) of
  +    case rand:uniform(3) of
   	1 -> {ok, rand_term()}; % careful
   	2 -> {1, 2, 3};
   	3 -> {<<"yep">>, 1337}
       end.
   
   rand_list() ->
  -    case random:uniform(3) of
  +    case rand:uniform(3) of
   	1 -> "hi";
   	2 -> [1,rand_term()]; % careful
   	3 -> [improper|list]
       end.
   
   rand_map() ->
  -    case random:uniform(3) of
  +    case rand:uniform(3) of
   	1 -> #{ hi => 3 };
   	2 -> #{ wat => rand_term(), other => 3 };  % careful
   	3 -> #{ hi => 42, other => 42, yet_anoter => 1337 }
  
positive.code:     end.
  
  rand_binary() ->
      case random:uniform(3) of
  	1 -> <<>>;
  	2 -> <<"hi">>;
  	3 -> <<"message text larger than 64 bytes. yep, message text larger than 64 bytes.">>
      end.
  
  rand_number() ->
      case random:uniform(3) of
  	1 -> random:uniform(5);
  	2 -> float(random:uniform(5));
  	3 -> 1 bsl (63 + random:uniform(3))
      end.
  
  rand_atom() ->
      case random:uniform(3) of
  	1 -> hi;
  	2 -> some_atom;
  	3 -> some_other_atom
  
negative.code: rand_terms(N) -> [rand_term()|rand_terms(N-1)].
  
  rand_term() ->
      case rand:uniform(6) of
  	1 -> rand_binary();
  	2 -> rand_number();
  	3 -> rand_atom();
  