anchor.diff:  handle_call(unique, _From, #state{is_fixed=true, unique_counter=N} = State) ->
       Id = make_unique_fixed(N),
       {reply, Id, State#state{unique_counter=N+1}};
  -
  -handle_call(number, _From, #state{is_fixed=true} = State) ->
  -    Number = random:uniform(1000000000), 
  -    {reply, Number, State};
   
   handle_call({number, Max}, _From, #state{is_fixed=true} = State) ->
       Number = random:uniform(Max),
  
positive.code: %% Length of session keys, used for the cookies, must be unique
  -define(ID_LENGTH,20).
  -define(OPTID_LENGTH,6).
  
  %% Range of random numbers returned
  -define(RANDOM_RANGE, 2000000000).
  
  %% gen_server exports
  -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
  
negative.code:     Id = make_unique(),
      {reply, Id, State};
  
  handle_call({number, Max}, _From, #state{is_fixed=false} = State) ->
      Number = crypto:rand_uniform(1, Max+1),
      {reply, Number, State};
  