Using Timer Coroutine
=====================
A timer instance is created with :py:class:`atimer.Timer` class. To delay
execution, await the timer object. The result of the await expression is
a number of timer expirations.

The example below creates timer object with 250 ms interval, arms the
timer, and uses the timer six times in the loop (the purpose of the if
statement is explained below).

.. literalinclude:: ../examples/time-show.py
   :lines: 20-41

The output of the example shows loop iteration counter, current system
clock value, and number of expirations::

    0: 1548799590.000  1
    1: 1548799590.250  1
    2: 1548799590.500  1
    3: 1548799591.602  4
    4: 1548799591.750  1
    5: 1548799592.000  1

The following properties of the timer can be noticed

- the difference between each execution is 250ms; this is despite the
  the time needed for execution of all the statements within the loop
- almost all timer expirations are synchronized with system clock at the
  edge of the 250 ms interval
- one expiration (loop iteration `3`) is affected by overrun due to the
  `time.sleep` statement; however, the timer corrects itself, and continues
  delayed execution at expected pace

.. vim: sw=4:et:ai