createExam(ident uid, ident id, string title, string date, string time, string location) {
  assume exists //accounts/account[uid]/admin;
 
  assume not exists //exams/exam[id];
 
  insert //exams
    <exam id=[id] title=[title] date=[date] time=[time] location=[location] free=[false] published=[false] >
      <tasks />
      <grades />
      <results />
    </exam>;
}