When running unit tests, it is useful to have the ability to flush old messages, in order to acquire the most up-to-date ones. In the example below, it would be useful to `flush()` after `asyncio.sleep()`: 
When running unit tests, it is useful to have the ability to flush old messages, in order to acquire the most up-to-date ones.
In the example below, it would be useful to
flush()afterasyncio.sleep():