Returns the current simulation datetime.

        Parameters
        ----------
        tz : tzinfo or str, optional
            The timezone to return the datetime in. This defaults to utc.

        Returns
        -------
        dt : datetime
            The current simulation datetime converted to ``tz``.

def get_datetime(self, tz=None):
        """
        Returns the current simulation datetime.

        Parameters
        ----------
        tz : tzinfo or str, optional
            The timezone to return the datetime in. This defaults to utc.

        Returns
        -------
        dt : datetime
            The current simulation datetime converted to ``tz``.
        """
        dt = self.datetime
        assert dt.tzinfo == pytz.utc, "Algorithm should have a utc datetime"
        if tz is not None:
            dt = dt.astimezone(tz)
        return dt