public function setTargetTemperatures($temp_low, $temp_high, $serial_number = NULL) {
        $serial_number = $this->getDefaultSerial($serial_number);
        $temp_low = $this->temperatureInCelsius($temp_low, $serial_number);
        $temp_high = $this->temperatureInCelsius($temp_high, $serial_number);
        $data = json_encode(array('target_change_pending' => TRUE, 'target_temperature_low' => $temp_low, 'target_temperature_high' => $temp_high));
        return $this->doPOST("/v2/put/shared." . $serial_number, $data);
    }