How to use drush to take any Drupal website offline or online?

For Drupal 7 :

drush vset maintenance_mode 1  // To take website into maintenance mode
drush vset maintenance_mode 0  // To take website into live mode

For Drupal 6 :

drush vset site_offline 1  // To take website into maintenance mode
drush vset site_offline 0  // To take website into live mode