Book Sort for BookDonkeyBot

Sort function

def sort_books(all_books, booktup) -> list:
    # Remove books that not match language or extension
    valid_books = all_books
    if booktup.lang:
        for book in list(all_books):
            if book[2].lower() != booktup.lang.lower():
                valid_books.remove(book)
    if booktup.ext:
        for book in list(all_books):
            if book[4].lower() != booktup.ext.lower():
                valid_books.remove(book)
    return valid_books