code: public function temperatureInUserScale($temperature_in_celsius, $serial_number = NULL) {
          $serial_number = $this->getDefaultSerial($serial_number);
          $temp_scale = $this->getDeviceTemperatureScale($serial_number);
          if ($temp_scale == 'F') {
              return ($temperature_in_celsius * 1.8) + 32;
          }
          return $temperature_in_celsius;
      }
docs: Convert a temperature value from Celsius to the device-preferred scale.
  
  @param float  $temperature_in_celsius The temperature to convert.
  @param string $serial_number          The thermostat serial number. Defaults to the first device of the account.
  
  @return float Temperature in device-preferred scale.