How to use the pytradfri.device.DeviceInfo function in pytradfri

def device_info(self):
        return DeviceInfo(self)

def power_source_str(self):
        """String representation of current power source."""
        if DeviceInfo.ATTR_POWER_SOURCE not in self.raw:
            return None
        return DeviceInfo.VALUE_POWER_SOURCES.get(self.power_source, 'Unknown')

def serial(self):
        """Serial number string."""
        return self.raw.get(DeviceInfo.ATTR_SERIAL)

def battery_level(self):
        """Battery in 0..100"""
        return self.raw.get(DeviceInfo.ATTR_BATTERY)

def power_source(self):
        """Power source."""
        return self.raw.get(DeviceInfo.ATTR_POWER_SOURCE)

def manufacturer(self):
        """Human readable manufacturer name."""
        return self.raw.get(DeviceInfo.ATTR_MANUFACTURER)

def model_number(self):
        """A model identifier string (manufactuer specified string)."""
        return self.raw.get(DeviceInfo.ATTR_MODEL_NUMBER)

def firmware_version(self):
        """Current firmware version string of the device."""
        return self.raw.get(DeviceInfo.ATTR_FIRMWARE_VERSION)