anchor.diff:      gen_server:call(?SERVER, generate).
   
   init([]) -> 
  -    random:seed(now()),
  +    rand:seed(exs1024s),
       {ok, []}.
   
   handle_call(generate, _From, State) ->
  
positive.code: 
  
  v4() ->
      v4(random:uniform(16#FFFFFFFFFFFF), random:uniform(16#FFF), 
              random:uniform(16#FFFFFFFF), random:uniform(16#3FFFFFFF)).
  v4(R1, R2, R3, R4) ->
      <<R1:48, 4:4, R2:12, 2:2, R3:32, R4: 30>>.
  to_string(U) ->
  
negative.code: % from http://stackoverflow.com/questions/1657204/erlang-uuid-generator
  -module(uuid).
  -behaviour(gen_server).
  
  %% API
  -export([start_link/0, generate/0]).
  