>>> s = py.Site('en')
>>> x = s.notifications()
>>> y = next(x)
WARNING: API error unknown_notformat: Unrecognized value for parameter "notformat": text.

Traceback (most recent call last):
  File "<pyshell#16>", line 1, in <module>
    y = next(x)
  File "pywikibot\site.py", line 2333, in notifications
    params['not' + key] = kwargs[key]
  File "pywikibot\data\api.py", line 2273, in submit
    raise APIError(**result['error'])
APIError: unknown_notformat: Unrecognized value for parameter "notformat": text. [help:See https://en.wikipedia.org/w/api.php for API usage. Subscribe to the mediawiki-api-announce mailing list at &lt;https://lists.wikimedia.org/mailman/listinfo/mediawiki-api-announce&gt; for notice of API deprecations and breaking changes.]