Tell the user (via desktop notification) when a command completes.
Requires the notify2 package (python3-notify2 on Ubuntu).
## Example Usage
Quick alert for 5 minutes from now:
`tell sleep 300`
Ping machines from a list and fail if one of them is offline.
tell 'while read machine;
ping -c 1 $machine || exit 1
done < machines'
TODO: Brief introduction on what you do with files - including link to relevant help section.