docs: def sample(ctx, element, timestamp, repeat, delay):
      """Sample the value of a vehicle data element
  
  This command allows for the current value of a vehicle data element
  to be sampled:
  
  \b
      $ wva vehicle sample VehicleSpeed
      168.15329
  
  Optionally, the value may be samples multiple times:
  
  \b
      $ wva vehicle sample VehicleSpeed --repeat 10 --delay 1 --timestamp
      148.076462 at Tue Mar 24 23:52:56 2015
      145.564896 at Tue Mar 24 23:52:57 2015
      143.057251 at Tue Mar 24 23:52:58 2015
      138.03804 at Tue Mar 24 23:52:59 2015
      135.526474 at Tue Mar 24 23:53:00 2015
      133.018829 at Tue Mar 24 23:53:01 2015
      130.507263 at Tue Mar 24 23:53:02 2015
      127.999619 at Tue Mar 24 23:53:03 2015
      125.48806 at Tue Mar 24 23:53:04 2015
      122.976501 at Tue Mar 24 23:53:05 2015
  
  For receiving large amounts of data on a periodic basis, use of subscriptions
  and streams is enocuraged as it will be significantly more efficient.
  """
      element = get_wva(ctx).get_vehicle_data_element(element)
      for i in xrange(repeat):
          curval = element.sample()
          if timestamp:
              print("{} at {}".format(curval.value, curval.timestamp.ctime()))
          else:
              print("{}".format(curval.value))
  
          if i + 1 < repeat:  # do not delay on last iteration
              time.sleep(delay)