public static function userName($name = null)
    {
        if ($name === null) {
            if (rand(1, 10) > 5) {
                $name = Name::firstName() . ' ' . Name::lastName();
            } else {
                $name = Name::firstName();
            }
        }

        $glue = array('.', '_');
        shuffle($glue);
        $nameParts = explode(' ', $name);
        shuffle($nameParts);
        $userName = implode($glue[0], $nameParts);

        return strtolower($userName);
    }