{
  alt {
    A -> B [label = label, note = note];
    alt {
      A -> B [label = label, note = note];
    }
  }
  alt {
    alt {
      alt {
        A -> B [label = label, note = note];
      }
    }
  }
  alt {
    A -> B [label = label, note = note];
  }
}
