pocketmine\level\format\FullChunk::toBinary PHP Method

    public function toBinary();

 public function writeChunk(FullChunk $chunk)
 {
     $this->lastUsed = \time();
     $chunkData = $chunk->toBinary();
     if ($chunkData !== \false) {
         $this->saveChunk($chunk->getX() - $this->getX() * 32, $chunk->getZ() - $this->getZ() * 32, $chunkData);
     }
 }