code: def set_sleep_timer(self, sleep_time_seconds):
          
          # Note: A value of None for sleep_time_seconds is valid, and needs to
          # be preserved distinctly separate from 0. 0 means go to sleep now,
          # which will immediately start the sound tappering, and could be a
          # useful feature, while None means cancel the current timer
          try:
              if sleep_time_seconds is None:
                  sleep_time = ''
              else:
                  sleep_time = format(
                      datetime.timedelta(seconds=int(sleep_time_seconds))
                  )
              self.avTransport.ConfigureSleepTimer([
                  ('InstanceID', 0),
                  ('NewSleepTimerDuration', sleep_time),
              ])
          except SoCoUPnPException as err:
              if 'Error 402 received' in str(err):
                  raise ValueError('invalid sleep_time_seconds, must be integer \
                      value between 0 and 86399 inclusive or None')
              raise
          except ValueError:
              raise ValueError('invalid sleep_time_seconds, must be integer \
                  value between 0 and 86399 inclusive or None')
docs: Sets the sleep timer.
  
          Args:
              sleep_time_seconds (int or NoneType): How long to wait before
                  turning off speaker in seconds, None to cancel a sleep timer.
                  Maximum value of 86399
  
          Raises:
              SoCoException: Upon errors interacting with Sonos controller
              ValueError: Argument/Syntax errors