def to_df(self, method: str = 'MEMORY', **kwargs) -> 'pd.DataFrame':
        """
        Export this SAS Data Set to a Pandas Data Frame

        :param method: defaults to MEMORY; the original method. CSV is the other choice which uses an intermediary csv file; faster for large data
        :param kwargs:
        :return: Pandas data frame
        """
        ll = self._is_valid()
        if ll:
            print(ll['LOG'])
            return None
        else:
            return self.sas.sasdata2dataframe(self.table, self.libref, self.dsopts, method, **kwargs)