def calibration_time(self, tz: datetime.tzinfo | None = None) -> datetime.datetime:
        """Return a python datetime object for the calibration time.

        Args:
            tz: The timezone for the string. If None, the method uses the platform's local timezone.

        Returns:
            A `datetime` object with the time.
        """
        # Python datetime only like microseconds, not milliseconds, and does not like 'Z'.
        first, second = self._calibration_dict['date'].split('.')
        modified_date = f'{first}.{second[:3]}'
        dt = datetime.datetime.strptime(modified_date, '%Y-%m-%dT%H:%M:%S.%f')
        return dt.replace(tzinfo=datetime.timezone.utc).astimezone(tz=tz)
Return a python datetime object for the calibration time.

        Args:
            tz: The timezone for the string. If None, the method uses the platform's local timezone.

        Returns:
            A `datetime` object with the time.
        
cirq-ionq/cirq_ionq/calibration.py