def METHOD_NAME(self, topic_arn, sub_arns, error_code=None):
    expected_params = {'TopicArn': topic_arn}
    response = {'Subscriptions': [{'SubscriptionArn': arn} for arn in sub_arns]}
    self._stub_bifurcator(
        'list_subscriptions_by_topic', expected_params, response,
        error_code=error_code)