interface I {
  in void e();
  behaviour {
    on e: {}
  }
}

interface II {
  in void e();
  out void cb();
  behaviour {
    bool busy = false;
    [!busy]
       on e: busy = true;
    [busy] {
       on e: illegal;
       on inevitable: { cb; busy = false; }
    }
  }
}

component SimpleBlocking3 {
  provides I p;
  requires II r;
  behaviour {
    bool busy = false;
    [!busy] {
       blocking on p.e(): { r.e(); busy = true; }
       on r.cb(): illegal;
    }
    [busy] {
       on p.e(): illegal;
       blocking on r.cb(): { p.reply(); busy = false; }
    }
  }
}