def format_website_string(website):
    """Returns a formatted website string to be used for siteinfo.
    Args:
        website (string): user-supplied.
    Returns:
        string: lower-case, prefixes removed.
    """
    formatted = website.lower()
    prefixes = ["https://", "http://", "www."]
    for prefix in prefixes:
        if formatted.startswith(prefix):
            formatted = formatted[len(prefix) :]
    return formatted