Using Ao_timer for a better sleep (See related posts)

A few of my old examples include 'unsafe' use of e32.ao_sleep().
The problem is that the sleep can't be interrupted.
I often use a convenient loop like this

while running:
  // do something
  e32.ao_sleep(1)  # sleep a sec

Now in pys60 1.3.1, it's better to use e32.Ao_timer

timer = e32.Ao_timer()
while running:
  // do something
  timer.after(1)   # sleep a sec

I can then interupt the sleep with

timer.cancel()

in other part of the program if I need to continue the loop.

For example, I can end the application without waiting for
the last second.