Returns a list of the subscriptions to a specific topic.
            
 Declaration Syntax
 Declaration Syntax| C# | 
ListSubscriptionsByTopicResponse ListSubscriptionsByTopic( ListSubscriptionsByTopicRequest request )
 Parameters
 Parameters- request (ListSubscriptionsByTopicRequest)
- List Subscriptions By Topic request
 Return Value
 Return ValueList Subscriptions By Topic  Response from the service
 Remarks
 Remarks
            Each call returns a limited list of subscriptions. If there are more subscriptions,
            a NextToken is also returned. Use the NextToken parameter in a new ListSubscriptionsByTopic
            call to get further results.