'Retrieve latest state.'

def update(self):

    if (self.device.temperature_scale == 'C'):
        self._unit = TEMP_CELSIUS
    else:
        self._unit = TEMP_FAHRENHEIT
    temp = getattr(self.device, self.variable)
    if (temp is None):
        self._state = None
    if isinstance(temp, tuple):
        (low, high) = temp
        self._state = ('%s-%s' % (int(low), int(high)))
    else:
        self._state = round(temp, 1)
