public function download($filename = null)
    {
        $filename = $filename ?: date('Y-m-d_His') . '.csv';
        $this->writer->output($filename);
    }
public function download($filename = null)
    {
        $filename = $filename ?: date('Y-m-d_His') . '.csv';
        $this->writer->output($filename);
    }
public function download ( $ filename = null ) { $ filename = $ filename ? : date ( 'Y-m-d_His' ) . '.csv' ; $ this -> writer -> output ( $ filename ) ; }
Download the CSV file.

@param string|null $filename
@return void
Download the CSV file .