def get_comments(self, card_id):
        """ Returns an iterator for the comments on a certain card. """
        params = {'filter': 'commentCard', 'memberCreator_fields': 'username'}
        comments = self.api_request(
            "/1/cards/{card_id}/actions".format(card_id=card_id),
            **params)
        for comment in comments:
            assert comment['type'] == 'commentCard'
            yield comment
Returns an iterator for the comments on a certain card.