code: def rate_timestamp(self, rate_timestamp):
          
          if rate_timestamp is not None:
              if isinstance(rate_timestamp, (str, type_check)):
                  rate_timestamp = parse(rate_timestamp).replace(tzinfo=pytz.utc)
              if type(rate_timestamp) == date:
                  rate_timestamp = datetime.combine(rate_timestamp, datetime.min.time()).replace(tzinfo=pytz.utc)
              if not rate_timestamp.tzinfo:
                  raise ValueError('Cannot set an FX rate timestamp without a timezone')
              self._rate_timestamp = rate_timestamp
docs: Force the rate_timestamp to be a datetime
          :param rate_timestamp:
          :return: