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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def trigger(self):
 """ 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. """

        self._trigger, value = self.get_attr_from_set(self._trigger, 'trigger')
        return value