anchor.diff:          Class:Exception:Stacktrace ->
               {error, {Class, Exception, Stacktrace}}
       end.
  +
  +maybe_update_interarrival_timer(#state{tref = undefined} = State) ->
  +    State;
  +maybe_update_interarrival_timer(#state{tref = TRef} = State) ->
  +    {ok, cancel} = timer:cancel(TRef),
  +    {ok, NewTRef} = timer:send_interval(interarrival(), start_user),
  +    State#state{tref = NewTRef}.
  
positive.code: 
  -required_variable(#{name => interarrival, value => 50, verification => positive_integer,
                       description => "a delay between creating the processes for two "
                                      "consecutive users (ms, def: 50ms)"}).
  
  -record(state, {scenario :: amoc:scenario() | undefined,
                  no_of_users = 0 :: user_count(),
  
negative.code: positive_integer(Interarrival) ->
      is_integer(Interarrival) andalso Interarrival > 0.
  
  maybe_update_interarrival_timer(interarrival, _) ->
      gen_server:cast(?SERVER, maybe_update_interarrival_timer).
  %% ------------------------------------------------------------------
  %% gen_server Function Definitions
  %% ------------------------------------------------------------------
  