create server1
create server2
OSError
sleep
create server3
OSError
create server4
server4 closed
sleep 0
CancelledError
sleep 1
create task server 1
CancelledError
sleep 2
create task server 2
CancelledError
sleep 3
create task server 3
CancelledError
sleep 4
create task server 4
CancelledError
done