Set the date for which symbols will be resolved to their assets
        (symbols may map to different firms or underlying assets at
        different times)

        Parameters
        ----------
        dt : datetime
            The new symbol lookup date.

def set_symbol_lookup_date(self, dt):
        """Set the date for which symbols will be resolved to their assets
        (symbols may map to different firms or underlying assets at
        different times)

        Parameters
        ----------
        dt : datetime
            The new symbol lookup date.
        """
        try:
            self._symbol_lookup_date = pd.Timestamp(dt, tz='UTC')
        except ValueError:
            raise UnsupportedDatetimeFormat(input=dt,
                                            method='set_symbol_lookup_date')