public override AmazonWebServiceResponse Unmarshall(XmlUnmarshallerContext context)
        {
            DescribeSecurityGroupsResponse response = new DescribeSecurityGroupsResponse();

            int originalDepth = context.CurrentDepth;
            int targetDepth = originalDepth + 1;
            if (context.IsStartOfDocument) 
               targetDepth = 2;

            while (context.ReadAtDepth(originalDepth))
            {
                if (context.IsStartElement || context.IsAttribute)
                {

                    if (context.TestExpression("securityGroupInfo/item", targetDepth))
                    {
                        var unmarshaller = SecurityGroupUnmarshaller.Instance;
                        var item = unmarshaller.Unmarshall(context);
                        response.SecurityGroups.Add(item);
                        continue;
                    }
                } 
            }

            return response;
        }
 public override AmazonWebServiceResponse Unmarshall(XmlUnmarshallerContext context) 
 {   
     DescribeSecurityGroupsResponse response = new DescribeSecurityGroupsResponse();
     
     int targetDepth = 2;
     while (context.Read())
     {
         if (context.IsStartElement || context.IsAttribute)
         {
             
             if (context.TestExpression("securityGroupInfo/item", targetDepth))
             {
                 response.SecurityGroups.Add(SecurityGroupUnmarshaller.GetInstance().Unmarshall(context));
                     
                 continue;
             }
         }
     }
          
                 
     return response;
 }