static IEvents PersonGenerator(IEnvironment env)
 {
     var womenToilet = env.NewResource(1);
     var menToilet = env.NewResource(1);
     var count = 0;
     while (true) {
         var rnd = env.Random.NextDouble();
         var gn = ((rnd<0.5) ? "Donna" : "Uomo") + count++;
         var tt = (rnd<0.5) ? womenToilet : menToilet;
         Console.WriteLine("{0:0.00}: {1} in coda",
                           env.Now, gn);
         env.Start(Person(env, gn, tt));
         var t = env.Random.Exponential(1.0/AvgPersonArrival);
         yield return env.Timeout(t);
     }
 }