code: def update(self, volume, display_name=None, display_description=None):
          
          uri = "/%s/%s" % (self.uri_base, utils.get_id(volume))
          param_dict = {}
          if display_name:
              param_dict["display_name"] = display_name
          if display_description:
              param_dict["display_description"] = display_description
          if not param_dict:
              # Nothing to do!
              return
          body = {"volume": param_dict}
          resp, resp_body = self.api.method_put(uri, body=body)
docs: Update the specified values on the specified volume. You may specify
          one or more values to update. If no values are specified as non-None,
          the call is a no-op; no exception will be raised.