createEmptyStats() {
  remove /stats; # procedures only operate on valid documents, so we have to get rid of "whatever was there" before
  insert / 
    <stats revision=0>
      <accounts>
        <account username="admin" lastName="admin" firstName="admin" email="admin@stats.system" password="some hash of 'admin'">
          <admin />
        </account>
      </accounts>
      <exercises />
      <exams />
    </stats>;
}