private static string GetNextToken( GetFeedSubmissionListByNextTokenResponse nextResponse )
 {
     return nextResponse.IsSetGetFeedSubmissionListByNextTokenResult()
         && nextResponse.GetFeedSubmissionListByNextTokenResult.HasNext
         ? nextResponse.GetFeedSubmissionListByNextTokenResult.NextToken
         : null;
 }
 private static IEnumerable<MwsFeedSubmissionDescriptor> TryGetFeedSubmissionDescriptors(
     GetFeedSubmissionListByNextTokenResponse response)
 {
     try {
         return ToFeedSubmissionDescriptors( response.GetFeedSubmissionListByNextTokenResult.FeedSubmissionInfo );
     }
     catch( Exception exception ) {
         throw new SpreadbotException( "TryGetFeedSubmissionDescriptors [{0}]", exception.Message );
     }
 }