code: func (c Client) Cleanup() error {
  	//conn := c.Pool.Get()
  	//defer conn.Close()
  	//
  	//cols := []string{
  	//	db.Transmission, db.Notification,
  	//}
  	//
  	//for _, col := range cols {
  	//	err := unlinkCollection(conn, col)
  	//	if err != nil {
  	//		return err
  	//	}
  	//}
  	err := c.CleanupOld(0)
  	if err != nil {
  		return err
  	}
  	return nil
  }
docs: // Cleanup delete all notifications and associated transmissions