system/Events/Events.php
public static function listeners($event_name): array
	{
		if (! isset(static::$listeners[$event_name]))
		{
			return [];
		}

		// The list is not sorted
		if (! static::$listeners[$event_name][0])
		{
			// Sort it!
			array_multisort(static::$listeners[$event_name][1], SORT_NUMERIC, static::$listeners[$event_name][2]);

			// Mark it as sorted already!
			static::$listeners[$event_name][0] = true;
		}

		return static::$listeners[$event_name][2];
	}
public static function listeners($event_name): array
	{
		if (! isset(static::$listeners[$event_name]))
		{
			return [];
		}

		// The list is not sorted
		if (! static::$listeners[$event_name][0])
		{
			// Sort it!
			array_multisort(static::$listeners[$event_name][1], SORT_NUMERIC, static::$listeners[$event_name][2]);

			// Mark it as sorted already!
			static::$listeners[$event_name][0] = true;
		}

		return static::$listeners[$event_name][2];
	}
Returns an array of listeners for a single event. They are
sorted by priority.

If the listener could not be found, returns FALSE, or TRUE if
it was removed.

@param $event_name

@return array