This method is a proxy method for asyncio.sleep

        :param sleep_time: Sleep interval in seconds

        :returns: No return value.

async def sleep(self, sleep_time):
        """
        This method is a proxy method for asyncio.sleep

        :param sleep_time: Sleep interval in seconds

        :returns: No return value.
        """
        try:
            await asyncio.sleep(sleep_time)
        except RuntimeError:
            if self.log_output:
                logging.info('sleep exception')
            else:
                print('sleep exception')
            await self.shutdown()