public function addUser(\auth\model\User $newUser)
 {
     try {
         $userName = $newUser->getUserName();
         $passwordHash = $newUser->getPasswordHash();
         $isAdmin = $newUser->getIsAdmin();
         $sql = "INSERT INTO " . $this->table . "(user_name, password_hash, is_admin) VALUES( :userName, :passwordHash, :isAdmin)";
         $params = array(":userName" => $userName, ":passwordHash" => $passwordHash, ":isAdmin" => $isAdmin);
         return $this->query($sql, $params, true);
     } catch (\Exception $e) {
         throw $e;
     }
 }