Alarm instance upon creation.
Returns .nil if no object is attached.
oneSecond = .Alarm~new(1, .Target~new, "a second has passed")
call SysSleep 1.5 -- give Alarm time to trigger
oneSecond~cancel
::class Target inherit AlarmNotification
::method triggered -- called when Alarm triggers
use arg alarm
say alarm~attachment -- displays "a second has passed"