def _download_query(self, as_of):
c = self.institution.client()<EOL>q = c.bank_account_query(<EOL>number=self.number,<EOL>date=as_of,<EOL>account_type=self.account_type,<EOL>bank_id=self.routing_number)<EOL>return q<EOL>
Formulate the specific query needed for download

        Not intended to be called by developers directly.

        :param as_of: Date in 'YYYYMMDD' format
        :type as_of: string