private long link(int i) {
    return requireLinks()[i];
  }

  private void setLink(int i, long value) {
    requireLinks()[i] = value;
  }

  /*
   * We don't define getPredecessor+getSuccessor and setPredecessor+setSuccessor here because
   * they're defined above -- including logic to add and subtract 1 to map between the values stored