interface ITopon
{
  in void e();
  in void t();
  out void a();
  behaviour
    {
      bool b = false;
      bool c = false;
      on t: { a; }
      [b][!c] { on e: a; }
      [!b][!c] { on e: a; }
      [!c][!b] { on e: a; }
    }
}

component Topon
{
  provides ITopon i;

  behaviour
    {
      bool b = false;
      bool c = false;
      on i.t(): { i.a(); }
      [b][!c] { on i.e(): i.a(); }
      [!b][!c] { on i.e(): i.a(); }
      [!c][!b] { on i.e(): i.a(); }
    }
}