If IP can't make requests, raise BitQuotaExceeded. Called before generating numbers.

def _check_quota(self):
        """ If IP can't make requests, raise BitQuotaExceeded. Called before generating numbers. """
        self._request_remaining_quota_if_unset()
        if self.quota_estimate < self.quota_limit:
            raise BitQuotaExceeded(self.quota_estimate)