pocketmine\level\Level::getBlockSkyLightAt PHP Method

    public function getBlockSkyLightAt(int $x, int $y, int $z) : int
    {
        return $this->getChunk($x >> 4, $z >> 4, true)->getBlockSkyLight($x & 0xf, $y & 0x7f, $z & 0xf);
    }