interface modelingSilent {
  in void e();
  out void a1();
  out void a2();
  behaviour {

    void f() {
      f();
    }

    void g() {
      bool b = false;
      if (b) h();
    }

    void h() {
      bool b = false;
      if (b) g();
      else a1;
    }

    bool b = false;
    on e: {}
    on inevitable: b = true;
    on inevitable: {
      if (b) a1;
    }
    on optional: {
      if (b) a1; else a2;
    }
    on optional: {
      f();
    }
    on optional: {
      g();
    }
  }
}