code: def getTimeSinceLastUpdate(IOType):
      
      global last_update_times
      # assert(IOType in ['net', 'disk', 'process_disk'])
      current_time = time()
      last_time = last_update_times.get(IOType)
      if not last_time:
          time_since_update = 1
      else:
          time_since_update = current_time - last_time
      last_update_times[IOType] = current_time
      return time_since_update
docs: Return the elapsed time since last update.