code: def trigger(self):
          
          self._trigger, value = self.get_attr_from_set(self._trigger, 'trigger')
          return value
docs: Sets the LED trigger. A trigger is a kernel based source of LED events.
          Triggers can either be simple or complex. A simple trigger isn't
          configurable and is designed to slot into existing subsystems with
          minimal additional code. Examples are the `ide-disk` and `nand-disk`
          triggers.
  
          Complex triggers whilst available to all LEDs have LED specific
          parameters and work on a per LED basis. The `timer` trigger is an example.
          The `timer` trigger will periodically change the LED brightness between
          0 and the current brightness setting. The `on` and `off` time can
          be specified via `delay_{on,off}` attributes in milliseconds.
          You can change the brightness value of a LED independently of the timer
          trigger. However, if you set the brightness value to 0 it will
          also disable the `timer` trigger.