/**
  * List registered states.
  * 
  * @subcommand list-states
  */
 public function list_states($args, $assoc_args)
 {
     $states = Dictator::get_states();
     $items = array();
     foreach ($states as $name => $attributes) {
         $state_obj = new $attributes['class']();
         $regions = implode(',', array_keys($state_obj->get_regions()));
         $items[] = (object) array('state' => $name, 'regions' => $regions);
     }
     $formatter = new \WP_CLI\Formatter($assoc_args, array('state', 'regions'));
     $formatter->display_items($items);
 }