'Get the ``dict`` of show ids per series by querying the `shows.php` page.
:return: show id per series, lower case and without quotes.
:rtype: dict'

@region.cache_on_arguments(expiration_time=SHOW_EXPIRATION_TIME)
def _get_show_ids(self):

    logger.info('Getting    show    ids')
    r = self.session.get((self.server_url + 'shows.php'), timeout=10)
    r.raise_for_status()
    soup = ParserBeautifulSoup(r.content, ['lxml', 'html.parser'])
    show_ids = {}
    for show in soup.select('td.version    >    h3    >    a[href^="/show/"]'):
        show_ids[sanitize(show.text)] = int(show['href'][6:])
    logger.debug('Found    %d    show    ids', len(show_ids))
    return show_ids
