code: def curve_rates(self, curve_rates):
          
          if curve_rates is not None:
              if isinstance(curve_rates, str):
                  self._curve_rates = curve_rates
              else:
                  try:
                      self._curve_rates = json.dumps(curve_rates)
                  except TypeError:
                      raise TypeError('Passed in curve rates object are not json serializable.Please check the format')
docs: :param curve_rates:
          :return: