fix sleeping error

                if err:

                    logger.error('Error occurred: ' + err.text)

                    times_retry_login -= 1

                elif success:

                    logger.info('Login successful')

                    return

        except ConnectionError as err:

            logger.warn('Connection FAILED. Try again in ' + str(config['interval_retry_connection']) + ' sec.')

            times_retry_login -= 1

            logger.warn('Connection FAILED.')

        # If keep trying to login too many times, it may trigger security alarm on the CAS server

        logger.info('Try again in {time} sec. {attempt} attempt(s) remaining.'.format(time=config['interval_retry_connection'], attempt=times_retry_login))

        times_retry_login -= 1

        logger.info('{attempt} attempt(s) remaining.'.format(attempt=times_retry_login))

        if times_retry_login <= 0:

            logger.error('Attempts used up. The program will quit.')

            raise RetryError

        logger.info('Try again in {time} sec. '.format(time=config['interval_retry_connection']))

        sleep(config['interval_retry_connection'])

if __name__ == '__main__':