code: def create_dataset(self, in_stream):
          
          assert XLSX_IMPORT
          from io import BytesIO
          xlsx_book = openpyxl.load_workbook(BytesIO(in_stream), read_only=True)
  
          dataset = tablib.Dataset()
          sheet = xlsx_book.active
  
          # obtain generator
          rows = sheet.rows
          dataset.headers = [cell.value for cell in next(rows)]
  
          for row in rows:
              row_values = [cell.value for cell in row]
              dataset.append(row_values)
          return dataset
docs: Create dataset from first sheet.