title: Issue in fetching data from nested json to construct bar graph in d3
body: <p>here is the json data..
  [
             {
              "month":"2016-01",<br>
              "top_services":[
                       {
                      "domain":" EESEL-PROD-XCRM",
                      "service":" Subscriber-1_0",
                      "operation":" getSubscriberProfile",
                      "total_trans":333646
                   },
                   {
                      "domain":" EESEL-PROD-XCRM",
                      "service":" ProductQuery-3_0",
                      "operation":" listSubscriberProducts3",
                      "total_trans":242797
                   },
                   {
                      "domain":" ELYSEES-PROD",
                      "service":" GetCachedNetworkSettings-2_0",
                      "operation":" electroencephalographic",
                      "total_trans":242123
                   },
               ]
             }
          ]</p>