docs: public static SeqServerGroup parse(String asg) {
      int d1 = asg.indexOf('-');
      int d2 = asg.indexOf('-', d1 + 1);
      int dN = asg.lastIndexOf('-');
      if (dN < 0 || !isSequence(asg, dN)) {
        dN = asg.length();
      }
      return new SeqServerGroup(asg, d1, d2, dN);
    }