def format_book_list(book_list):
    """Formats the list of books into a single string message to send """ 
    text_to_send = ""
    for book in book_list: 
        if book.current_price == "Book out of stock": 
            text_to_send += f"{book.title}\n{book.current_price}\nDiscount: {book.discount}% \n\n"    
        else: 
            text_to_send += f"{book.title}\nPrice: {book.current_price}€\nDiscount: {book.discount}% \n\n"
    return text_to_send