public function insert(int $offset, Period $interval, Period ...$intervals): void
    {
        if ($offset < 0 || $offset > count($this->intervals)) {
            throw new InvalidIndex(sprintf('%s is an invalid offset in the current sequence', $offset));
        }

        array_unshift($intervals, $interval);
        array_splice($this->intervals, $offset, 0, $intervals);
    }