interface ISimple
{
  in void e();
  out void a();

  behaviour
  {
    bool On = false;
    on e: [On] { On = !On; }
    on e: [!On] { a; On = !On; }
  }
}

component Simpleint
{
  provides ISimple p;

  behaviour
  {
    subint S {-1..1};
    S s = 1;
    on p.e(): [s == 0] { s = 1; }
    on p.e(): [s == 1] { p.a(); s = 0; }
  }
}