pocketmine\nbt\NBT::putInt PHP Method

    public function putInt($v)
    {
        $this->buffer .= $this->endianness === self::BIG_ENDIAN ? Binary::writeInt($v) : Binary::writeLInt($v);
    }

 public function write(NBT $nbt)
 {
     $nbt->putInt(strlen($this->value));
     $nbt->put($this->value);
 }