anchor.diff:  
   
   v4() ->
  -    v4(random:uniform(16#FFFFFFFFFFFF), random:uniform(16#FFF), 
  -            random:uniform(16#FFFFFFFF), random:uniform(16#3FFFFFFF)).
  +    v4(rand:uniform(16#FFFFFFFFFFFF), rand:uniform(16#FFF),
  +       rand:uniform(16#FFFFFFFF), rand:uniform(16#3FFFFFFF)).
   v4(R1, R2, R3, R4) ->
       <<R1:48, 4:4, R2:12, 2:2, R3:32, R4: 30>>.
   to_string(U) ->
  
positive.code:     gen_server:call(?SERVER, generate).
  
  init([]) -> 
      random:seed(now()),
      {ok, []}.
  
  handle_call(generate, _From, State) ->
  
negative.code: % from http://stackoverflow.com/questions/1657204/erlang-uuid-generator
  -module(uuid).
  -behaviour(gen_server).
  
  %% API
  -export([start_link/0, generate/0]).
  