code: def delay_on(self):
          
  
          # Workaround for ev3dev/ev3dev#225.
          # 'delay_on' and 'delay_off' attributes are created when trigger is set
          # to 'timer', and destroyed when it is set to anything else.
          # This means the file cache may become outdated, and we may have to
          # reopen the file.
          for retry in (True, False):
              try:
                  self._delay_on, value = self.get_attr_int(self._delay_on, 'delay_on')
                  return value
              except OSError:
                  if retry:
                      self._delay_on = None
                  else:
                      raise
docs: The `timer` trigger will periodically change the LED brightness between
          0 and the current brightness setting. The `on` time can
          be specified via `delay_on` attribute in milliseconds.