We can retry a send if the error is transient and the number of
        attempts taken is fewer than the maximum allowed

def _can_retry(self, batch, error):
        """
        We can retry a send if the error is transient and the number of
        attempts taken is fewer than the maximum allowed
        """
        return (batch.attempts < self.config['retries']
                and getattr(error, 'retriable', False))