interface I1
{
  in void e();

  behaviour
  {
    on e: {}
  }
}

interface I2
{
  out void f();

  behaviour
  {
    on inevitable: f;
  }
}

component A
{
  provides I1 p;
  requires I1 r1;
  requires I2 r2;

  behaviour
  {
    on p.e(): r1.e();
    on r2.f(): r1.e();
  }
}

interface I3
{
  in void e();
  out void f();

  behaviour
  {
    bool pending = false;
    [!pending]
    {
      on e: pending = true;
    }
    [otherwise]
    {
      on e: illegal;
      on inevitable: {pending = false; f;}
    }
  }
}

component Blocked
{
  provides I1 p;
  requires I3 r;

  behaviour
  {
    blocking on p.e(): {r.e();}
    on r.f(): p.reply();
  }
}

component BlockedSystem1
{
  provides I1 p;
  requires I2 r2;
  requires I3 r3;

  system
  {
    A a;
    Blocked b;

    p <=> a.p;
    a.r1 <=> b.p;
    a.r2 <=> r2;
    b.r <=> r3;
  }
}