pocketmine\level\SimpleChunkManager::setBlockDataAt PHP Method

    public function setBlockDataAt(int $x, int $y, int $z, int $data)
    {
        if ($chunk = $this->getChunk($x >> 4, $z >> 4)) {
            $chunk->setBlockData($x & 0xf, $y & 0x7f, $z & 0xf, $data);
        }
    }