public function toArray($sheet_name,$ext=false)
  {
    if(!$ext){
      $ext=pathinfo($sheet_name, PATHINFO_EXTENSION);
    }
    switch ($ext) {
      case 'csv':
      $reader = ReaderFactory::create(Type::CSV);
      break;
      case 'ods':
      $reader = ReaderFactory::create(Type::ODS);
      break;
      case 'xlsx':
      $reader = ReaderFactory::create(Type::XLSX);
      break;
    }
    $reader->open($sheet_name);
    foreach ($reader->getSheetIterator() as $sheet) {
      $sheetName = $sheet->getName();
      foreach ($sheet->getRowIterator() as $row) {
        $list['lists'][$sheetName][]=$row;
      }
    }
    $reader->close();
    $lists=false;
    foreach ($list['lists'] as $key => $value) {
      $lists[$key]=$this->sheetToAlpha($value);
    }
    if($ext=="csv"){
      return $lists[""];
    }else{
      return $lists;
    }
  }