def fetch(self, category=CATEGORY_MESSAGE, from_date=DEFAULT_DATETIME):
items = super().fetch(category, from_date)<EOL>return items<EOL>
Fetch the messages from a Groups.io group.

        The method fetches the mbox files from a remote Groups.io group
        and retrieves the messages stored on them.

        :param category: the category of items to fetch
        :param from_date: obtain messages since this date

        :returns: a generator of messages