/**
  * Create a new onlinejudge type assignment activity
  *
  * @param object $assignment The data from the form
  * @return int The id of the assignment
  */
 function add_instance($assignment)
 {
     global $DB;
     // Add assignment instance
     $assignment->id = parent::add_instance($assignment);
     if ($assignment->id) {
         $onlinejudge = $assignment;
         $onlinejudge->assignment = $onlinejudge->id;
         $DB->insert_record('assignment_oj', $onlinejudge);
     }
     return $assignment->id;
 }