code: def blink(self, interval: float = 0.2, n: int = 3):
          
          for i in range(n):
              self.all_on()
              time.sleep(interval / 2)
              self.all_off()
              time.sleep(interval / 2)
docs: Blink all the lights on and off at once.
          NOTE! Does not remember prior state of lights and will finish
          with all lights off.
          :param interval: The length in seconds of an ON/OFF cycle
          :param n: How many times to cycle ON and OFF
          :return: