Can the returned events-bitmask include only `MYSQL_WAIT_TIMEOUT` flag?
The status that is being returned by a non-blocking operation is a bitmask of events to wait. It can be one of: MYSQL_WAIT_READ, MYSQL_WAIT_WRITE, MYSQL_WAIT_EXCEPT, MYSQL_WAIT_TIMEOUT. 1. Is it correct? are there any other options not listed above? 2. Is there a scenario in which the operation returns solely the flag `MYSQL_WAIT_TIMEOUT`?