def _authenticate_if_possible(self, email=None, password=None):
        """If possible - authenticate.  Mturk requires authentication for
        listing pagination pages greater that 20

        Return ``True`` if authentication was done successfully, else
        ``False``.
        """
        if self.mturk_email and self.mturk_password:
            auth.install_opener()
            resp = auth.authenticate(
                email=email or self.mturk_email,
                password=password or self.mturk_password
            )
            if resp.getcode() != 200:
                raise Exception(resp.read() % 'Authentiaction error: %s')
            log.info('Mturk authentication done')
            return True
        log.warning('No mturk authentication')
        return False
dataset/ETHPy150Open ipeirotis/Mturk-Tracker/app/mturk/main/management/commands/crawl.py/Command._authenticate_if_possible/swapped operands of `%`