public function setChunkSize($size)
    {
        if(static::MODE == 'cli' && is_numeric($size))
        {
            $this->chunkSize = (int)$size;
        }
        elseif(static::MODE == 'web')
        {
            throw new Exception('Chunk size is not supported on web mode');
        }
        else
        {
            throw new Exception("$size is not a valid chunk size");
        }

        return $this;
    }