private function chartData(string $symbol, string $interval, array $ticks)
    {
        if (!isset($this->info[$symbol])) {
            $this->info[$symbol] = [];
        }

        if (!isset($this->info[$symbol][$interval])) {
            $this->info[$symbol][$interval] = [];
        }

        $output = [];
        foreach ($ticks as $tick) {
            list($openTime, $open, $high, $low, $close, $assetVolume, $closeTime, $baseVolume, $trades, $assetBuyVolume, $takerBuyVolume, $ignored) = $tick;
            $output[$openTime] = [
                "open" => $open,
                "high" => $high,
                "low" => $low,
                "close" => $close,
                "volume" => $baseVolume,
                "openTime" => $openTime,
                "closeTime" => $closeTime,
                "assetVolume" => $assetVolume,
                "baseVolume" => $baseVolume,
                "trades" => $trades,
                "assetBuyVolume" => $assetBuyVolume,
                "takerBuyVolume" => $takerBuyVolume,
                "ignored" => $ignored,
            ];
        }

        if (isset($openTime)) {
            $this->info[$symbol][$interval]['firstOpen'] = $openTime;
        }

        return $output;
    }