code: def set_blink(self, frequency):
          
          if frequency not in [HT16K33_BLINK_OFF, HT16K33_BLINK_2HZ,
                               HT16K33_BLINK_1HZ, HT16K33_BLINK_HALFHZ]:
              raise ValueError('Frequency must be one of HT16K33_BLINK_OFF, HT16K33_BLINK_2HZ, HT16K33_BLINK_1HZ, or HT16K33_BLINK_HALFHZ.')
          self._device.writeList(HT16K33_BLINK_CMD | HT16K33_BLINK_DISPLAYON | frequency, [])
docs: Blink display at specified frequency.  Note that frequency must be a
          value allowed by the HT16K33, specifically one of: HT16K33_BLINK_OFF,
          HT16K33_BLINK_2HZ, HT16K33_BLINK_1HZ, or HT16K33_BLINK_HALFHZ.