'Read from sensor and update the state.'

def update(self):

    self._mhz_client.update()
    data = self._mhz_client.data
    self._temperature = data.get(SENSOR_TEMPERATURE)
    if ((self._temperature is not None) and (self._temp_unit == TEMP_FAHRENHEIT)):
        self._temperature = round(celsius_to_fahrenheit(self._temperature), 1)
    self._ppm = data.get(SENSOR_CO2)
