'Create dataset from first sheet.'

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
    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
