/**
  * Get account for entity.
  * If the account doesn't exist it will be created.
  */
 public static function getEntityAccount($entity_type, $entity_id)
 {
     if (!$entity_id) {
         throw new Exception("Expected entity id");
     }
     $account = self::findOneByQuery("SELECT * FROM %t WHERE entity_type=%s AND entity_id=%s", $entity_type, $entity_id);
     if (!$account) {
         $account = new Account($entity_type, $entity_id);
         $account->save();
     }
     return $account;
 }