pocketmine\level\Level::addChunkPacket PHP Method

    public function addChunkPacket(int $chunkX, int $chunkZ, DataPacket $packet)
    {
        if (!isset($this->chunkPackets[$index = Level::chunkHash($chunkX, $chunkZ)])) {
            $this->chunkPackets[$index] = [$packet];
        } else {
            $this->chunkPackets[$index][] = $packet;
        }
    }