public function period(string $period)
    {
        if (!in_array($period, Constants::PERIODS)) {
            throw new InvalidPeriodException('Request period is not valid. Valid values are defined in \Barryvanveen\Lastfm\Constants::PERIODS.');
        }

        $this->query = array_merge($this->query ?? [], ['period' => $period]);

        return $this;
    }