def comments(self):
        """
        Iterator of :class:`stravalib.model.ActivityComment` objects for this activity.
        """
        if self._comments is None:
            self.assert_bind_client()
            if self.comment_count > 0:
                self._comments = self.bind_client.get_activity_comments(self.id)
            else:
                # Shortcut if we know there aren't any
                self._comments = []
        return self._comments