code: def update(self):
          
          if not self._continuous_sampling \
                  or self._light_level < 0 \
                  or self._operation_mode != self._mode:
              self._reset()
              self._set_mode(self._operation_mode)
              self._wait_for_result()
          self._light_level = self._get_result()
          if not self._continuous_sampling:
              self._power_down()
docs: Update the measured light level in lux.