public static function check($specific = null)
	{
		$drivers = $specific === null ? static::$_instances : (array) $specific;

		foreach ($drivers as $i)
		{
			if ( ! static::$_verify_multiple && ! empty(static::$_verified))
			{
				return true;
			}

			$i = $i instanceof Auth_Login_Driver ? $i : static::instance($i);
			if ( ! array_key_exists($i->get_id(), static::$_verified))
			{
				$i->check();
			}

			if ($specific)
			{
				if (array_key_exists($i->get_id(), static::$_verified))
				{
					return true;
				}
			}
		}

		return $specific === null && ! empty(static::$_verified);
	}