code: func (ag *AuthGroup) Insert(db XODB) error {
  	var err error
  
  	// if already exist, bail
  	if ag._exists {
  		return errors.New("insert failed: already exists")
  	}
  
  	// sql insert query, primary key provided by sequence
  	const sqlstr = `INSERT INTO public.auth_group (` +
  		`name` +
  		`) VALUES (` +
  		`$1` +
  		`) RETURNING id`
  
  	// run query
  	XOLog(sqlstr, ag.Name)
  	err = db.QueryRow(sqlstr, ag.Name).Scan(&ag.ID)
  	if err != nil {
  		return err
  	}
  
  	// set existence
  	ag._exists = true
  
  	return nil
  }
docs: // Insert inserts the AuthGroup to the database.