interface TimerNotify
"""
Notifications for timer.
"""
fun ref apply(timer: Timer, count: U64): Bool =>
"""
Called with the the number of times the timer has fired since this was last
called. Return true to reschedule the timer (if it has an interval), or
false to cancel the timer (even if it has an interval).
"""
true
fun ref cancel(timer: Timer) =>
"""
Called if the timer is cancelled. This is also called if the notifier
returns false.
"""
None