interface ihelloworld
{
  in void hello();
  out void world();

  behavior
  {
    bool idle = true;
    on hello: idle = false;
    [!idle] {
      on inevitable: {idle = true; world;}
    }
  }
}

component compliance
{
  provides ihelloworld h;
  requires ihelloworld w;

  behavior
  {
    on h.hello(): w.hello();
    on w.world(): {}
  }
}