def edit_book_series_index(series_index, book):
    # Add default series_index to book
    modif_date = False
    series_index = series_index or '1'
    if not series_index.replace('.', '', 1).isdigit():
        flash(_("%(seriesindex)s is not a valid number, skipping", seriesindex=series_index), category="warning")
        return False
    if str(book.series_index) != series_index:
        book.series_index = series_index
        modif_date = True
    return modif_date
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.