interface ihello
{
  in void hello();
  out void world();
  
  behaviour
  {
    on hello: {}
  }
}

component hellocheckcompbindings
{
  provides ihello p;
  requires ihello r;
  
  behaviour
  {
    on p.hello(): {
      r.hello();
    }
    on r.world(): {
      p.world();
    }
  }
}