code: def get_body(self):
          
  
          raw_body = yield get_arg(self, 2)
          if not self.serializer:
              raise tornado.gen.Return(raw_body)
          else:
              body = self.serializer.deserialize_body(raw_body)
              raise tornado.gen.Return(body)
docs: Get the body value from the response.
  
          :return: a future contains the deserialized value of body